Optometric apparatus

ABSTRACT

An optometric apparatus for correcting the refraction of an eye to be examined, which allows even a person who is inexperienced and unfamiliar with optometry to easily obtain appropriate prescription values, and conduct analysis of the visual function. The optometric apparatus has a rotary prism for imparting a prism power to the eye to be examined. An appropriate examination is conducted by using the rotary prism in accordance with a program stored in a memory to obtain the prism power of an expected state, and a result of examination is displayed.

BACKGROUND OF THE INVENTION

The present invention relates to an optometric apparatus suitable forcorrection of refraction and visual function analysis of an eye to beexamined.

When a refractive error (ametropia) is present in an eye to be examinedand is to be corrected, it is important to prescribe such a power thatwill not impart an uneasy sensation and fatigue to a subject in wearingthe spectacles after accurately examining the refractive state of theeye to be examined and by taking into consideration the complaints ofthe subject and powers of the former spectacles. In addition, if avisual function error such as phoria is present in the eye to beexamined, it is necessary to analyze that visual function correctly andcorrect the same.

When determining a prescription power, a perfectly corrected refractivepower test is generally conducted on the basis of data on examinationsuch as an objective examination using a so-called refractometer and themeasurement of powers of the former spectacles using a lens meter. Inthe perfectly corrected refractive power test, a subjective-typerefractive-power measuring device in which optical elements havingvarious optical characteristics are selectively disposed in test windowsis used, responses on appearances of a presented test target (chart) isobtained from the subject, and a power at which maximum visual acuitycan be obtained is determined. After a perfect correction power isobtained in the perfectly corrected refractive power test, the poweradjustment is made on the basis of this power and the like, andprescription values are derived.

However, the procedure for deriving appropriate prescription valuesafter obtaining the perfect correction power and adjusting that powerlargely depends on the knowledge and experience of the examiner, and isnot easy for an inexperienced person.

There have been problems in that, particularly in a case where a visualfunction error such as phoria is present in the eye to be examined,substantial time is generally required in deriving prescription valuesafter making power adjustment, and that there are differences in thederived prescription values among individual examiners.

SUMMARY OF THE INVENTION

A technical object of the present invention is to provide an optometricapparatus which allows even a person who is inexperienced and unfamiliarwith optometry to easily obtain appropriate prescription values, andconduct analysis of the visual function.

To attain the above-noted object, the present invention provides thefollowings:

(1) An optometric apparatus for correcting refraction of an eye to beexamined, comprising:

a rotary prism for imparting a prism power to the eye to be examined;

program storing means for storing a program for conducting examinationby using the rotary prism;

program advancing means for advancing the program;

prism-power storing means for storing a prism power of an expectedstate; and

display means for displaying a result of examination.

(2) An optometric apparatus according to (1), wherein the program storedin the program storing means includes a program in which an operatingmethod in an examination process is displayed by the display means.

(3) An optometric apparatus according to (1), wherein the program storedin the program storing means includes at least one of a horizontalphoria test, a vertical phoria test, a divergence test, and aconvergence test.

(4) An optometric apparatus according to (3), wherein tests for far useand near use are included in each of the tests.

(5) An optometric apparatus according to (1), wherein the program storedin the program storing means includes at least one of anear-point-of-convergence test, a near-point-of-accommodation test, anda near accommodation test.

(6) An optometric apparatus according to (5), further comprising:

input means for inputting a distance from a root of a nose at the timeof the near-point-of-convergence test or the near-point-of-accommodationtest; and

calculating means for effecting a predetermined calculation on the basisof the inputted distance.

(7) An optometric apparatus according to (1), wherein the result ofexamination displayed by the display means includes a result of analysisin which the result of examination is analyzed.

(8) A controller for operating a subjective-type refractive-powermeasuring device and a target presenting device in an optometricapparatus, the controller comprising:

a memory which stores therein a program for a visual function test to beexecuted after perfect correction values for both eyes are obtained;

a microcomputer circuit connected to the memory to control thesubjective-type refractive-power measuring device and the targetpresenting device in accordance with the program;

a switch section through which an examiner can control thesubjective-type target presenting device and can instruct whether acurrent test item of the visual function test should be continueddepending on a reply from a subject; and

a display on which an advice regarding how to control thesubjective-type target presenting device is displayed if the examinerinstructs, through the switch section, that the current test item shouldbe continued.

(9) A controller according to (8), wherein the memory automaticallystores therein a result of the current test item if the examinerinstructs that the current test item should not be continued.

(10) A controller designed for an optometric apparatus, comprising:

a memory which stores therein a program for a visual function testincluding at least one of horizontal phoria test, a vertical phoriatest, a divergence test, a convergence test, a near-point-of-convergencetest, a near-point-of-accommodation test, and a near accommodation test;

a microcomputer circuit connected to the memory;

a switch section connected to the microcomputer circuit; and

a display connected to the microcomputer circuit.

The present disclosure relates to the subject matter contained inJapanese patent application No. Hei. 9-190691 (filed on Jun. 30, 1997)which is expressly incorporated herein by reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an external view illustrating an overall configuration of anoptometric apparatus in accordance with an embodiment;

FIG. 2 is a view illustrating a sliding mechanism and a flappingmechanism of lens units;

FIG. 3 is a top view of a controller 5;

FIG. 4 is a block diagram illustrating the control of the apparatus inaccordance with the embodiment;

FIG. 5 is a diagram illustrating a flowchart of an optometric program inaccordance with the embodiment;

FIG. 6 is a diagram illustrating an example of a menu screen for settingwhich is displayed on a display;

FIG. 7 is a diagram illustrating an example of the screen for inputtingage;

FIG. 8 is a diagram illustrating an example of the screen at the time ofstarting the unaided visual acuity test;

FIG. 9 is a diagram illustrating a test flow in an astigmatism(cylinder) test;

FIG. 10 is a flowchart illustrating a program for automaticallyadjusting correction power for far use;

FIG. 11 is a flowchart illustrating the program for automaticallyadjusting correction power for far use;

FIG. 12 is a flowchart illustrating the program for automaticallyadjusting correction power for far use;

FIG. 13 is a flowchart illustrating the program for automaticallyadjusting correction power for far use;

FIG. 14 is a flowchart illustrating the program for automaticallyadjusting correction power for far use;

FIG. 15 is a flowchart illustrating the program for automaticallyadjusting correction power for far use;

FIG. 16 is a diagram illustrating calculation using tables A to table Dfor obtaining a correction amount for adjusting the correction power;

FIG. 17 is a diagram illustrating an example of the screen of thedisplay after automatic adjustment;

FIG. 18 is a flowchart illustrating an adjustment program for manualadjustment;

FIG. 19 is a flowchart illustrating the adjustment program for manualadjustment;

FIG. 20 is a diagram illustrating a specific example of adjustment ofastigmatism (cylinder) with respect to an input by a switch when anuneasy sensation is present in manual adjustment E;

FIG. 21 is a diagram illustrating an example of display when manualadjustment has been made with respect to automatically adjusted powers;

FIG. 22 is a diagram illustrating the display of an operationalinstruction when a necessary near-work distance is inputted;

FIG. 23 is a diagram illustrating an example of a print;

FIG. 24 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 25 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 26 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 27 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 28 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 29 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 30 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 31 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 32 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 33 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 34 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 35 is a diagram illustrating a flowchart of a visual functiontesting program in accordance with the embodiment;

FIG. 36 is a diagram illustrating an example of the screen of thedisplay in a far horizontal phoria test;

FIG. 37 is a diagram illustrating an example of the a screen of thedisplay in a far vertical phoria test;

FIG. 38 is a diagram illustrating an example of the screen of thedisplay in a far divergence test;

FIG. 39 is a diagram illustrating an example of the screen of thedisplay in a far convergence test;

FIG. 40 is a diagram illustrating an example of the screen of thedisplay in a near-point-of-convergence test;

FIG. 41 is a diagram illustrating an example of the screen of thedisplay in a near point of accommodation test;

FIG. 42 is a diagram illustrating an example of the screen of thedisplay in a near negative relative accommodation test;

FIG. 43 is a diagram illustrating an example of the screen of thedisplay in a near positive relative accommodation test;

FIG. 44 is a diagram illustrating an example of the screen of thedisplay of a table of data in a visual function test;

FIG. 45 is a diagram illustrating an example of the screen of thedisplay of a table of data in a visual function test;

FIG. 46 is a diagram illustrating an example of the screen of thedisplay of a table of data in a visual function test;

FIG. 47 is a diagram illustrating an example of the screen of thedisplay of a table of data in a visual function test;

FIG. 48 is a diagram illustrating an example of the screen of thedisplay of a table of data in a visual function test;

FIG. 49 is a diagram illustrating an example of the screen of thedisplay of graph data and AC/A (Accommodative Convergence/Accommodation)ratio in a visual function test;

FIG. 50 is a diagram illustrating an example of the screen displayingthe results of analysis and a method of prescription based on the AC/Aratio and the eye position;

FIG. 51 is a diagram illustrating an example of the screen displayingthe results of analysis and a method of prescription based on the Sheardcriteria;

FIG. 52 is a diagram illustrating an example of the screen displayingthe results of analysis and a method of prescription based on thePercival's criteria; and

FIG. 53 is a diagram illustrating an example of the screen displayingthe results of analysis and a method of prescription based on theMorgan's system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, a description will be given of anembodiment of the present invention. FIG. 1 is an external viewillustrating an overall configuration of an optometric apparatus inaccordance the embodiment.

Reference numeral 1 denotes an examination table disposed between asubject and an examiner, and reference numeral 2 denotes asubjective-type refractive-power measuring device. The subjective-typerefractive-power measuring device 2 is provided with a pair of left andright lens units 10 in which various optical elements are electricallydriven so as to be selectively disposed in a pair of test windows 11, aswell as a suspending portion 12 for suspending the left and right lensunits 10. The suspending portion 12 has a sliding mechanism forcorrecting the interval between the left and right lens units 10 and aflapping mechanism (which will be described later) for making theoptical axes of optical systems parallel with the visual axes in nearvision of the subject. Numeral 13 denotes a visual test chart for nearuse which is held by a near-point rod attached to the suspending portion12 (this visual test chart 13 is removed from the front of the eyesduring an examination for far use).

Numeral 3 denotes an objective-type ocular refractive-power measuringdevice for measuring the refractive power of the eye by projecting ameasuring index onto the eyeground of the subject eye and detecting aprojected image of the index on the eyeground by means of a lightreceiving means. The objective-type ocular refractive-power measuringdevice 3 has the function-of obtaining the interpupillary distance onthe basis of an amount of movement of its measuring section having ameasuring optical system when the measuring section is moved from astate of completion of alignment of one eye to a state of completion ofalignment of the other eye. The objective-type ocular refractive-powermeasuring device 3 is placed on a moving tray which is slidable on theexamination table 1, and during an objective examination theobjective-type ocular refractive-power measuring device 3 is slid to acentral position on the examination table 1 to execute measurement.

Numeral 4 denotes a projection-type target (chart) presenting device forpresenting test targets (charts). Numeral 5 denotes a controller foroperating the subjective-type refractive-power measuring device 2 andthe projection-type target (chart) presenting device 4, and numeral 6denotes a relay unit for relaying communication between the respectivedevices. A lens meter is also connected to the relay unit 6.

FIG. 2 is a diagram illustrating the sliding mechanism and the flappingmechanism of the lens units 10. A pair of shafts 201 are respectivelyfixed to a pair of suspending plates 200 for suspending the respectivelens units 10, and each shaft 201 is inserted in a hole 202a formed ineach of a pair of slide bases 202 and is rotatable for the flappingoperation. The slide bases 202 are slidable in the axial direction of afixed guide 203, and both a drive motor 204 for sliding and the fixedguide 203 are fixed to an unillustrated fixing bracket. Externallythreaded portions 205 and 206 having mutually different threadingdirections are formed on a shaft which is coupled to the drive motor204, and the externally threaded portions 205 and 206 mesh with internalthreads formed in the slide bases 202. Consequently, as the drive motor204 is rotated, the two slide bases 202 move in mutually oppositedirections. Thus, the interval between the left and right lens units 10can be adjusted, and the distance between the optical axes of theoptical systems disposed in the test windows 11 can be adjusted to theinterpupillary distance of the subject.

Numeral 207 denotes a drive motor for flapping, and worms 208 and 209having mutually different threading directions are fixed to a rotatingshaft of the drive motor 207 for flapping. Wheels 210 and 211 which meshwith these worms are respectively fixed to rotatable shafts 212 and 213.Eccentric shafts 214 and 215 and bearings 216 and 217 are respectivelydisposed at lower ends of the rotatable shafts 212 and 213, and thebearings 216 and 217 are respectively engaged in grooves 218 and 219formed in the suspending plates 200. Consequently, as the drive motor207 rotates, the left and right lens units 10 are flapped in mutuallyopposite directions via the suspending plates 200.

FIG. 3 is a top view of the controller 5.

Reference numeral 30 denotes a liquid-crystal display which displaysoptometric information. Numeral 31 denotes a switch section which isprovided with the following switches: a group of setting changeoverswitches 32 having switches which are used when changing over a displayscreen to a menu screen of the display 30 and effecting such as thesetting of parameters; a group of target (chart) switches 33 forchanging over a target (chart) to be presented from the target (chart)presenting device 4; a group of mask switches 34 for applying a masknecessary for the presented target (chart); a start switch 35 forexecuting programmed optometry; an advance switch 36 for advancing theitem of programmed optometry to an ensuing item; a group of mode-changedesignating switches 37 for designating a mode of such as measurementdata to be changed; a group of input-data designating switches 38 fordesignating a mode for entering data or a mode for measurement; a datainput switch 39 which is used when data from the objective-type ocularrefractive-power measuring device, a lens meter, and the like areinputted; a print switch 40; a measurement-eye designating switch 41;and a dial switch 42 which is used when changing measurement values andinputting numerical values.

Reference numerals 43a and 43b denote changeover switches for changingover a cross-cylinder, and these changeover switches 43a and 43b arealso used during adjustment of appearances in the stage of prescription.Numeral 44 denotes a shift switch, and if another switch is pressedwhile this switch is being pressed, a switch function can be added.Numeral 45 denotes a group of function switches which are used whenselecting switches corresponding to switch displays which are displayedat predetermined positions in a lower portion of the screen of thedisplay 30.

FIG. 4 is a block diagram for describing the control of the apparatus.

A switch signal from the switch section 31 of the controller 5 issubjected to predetermined processing, and is then inputted to amicrocomputer circuit 50. Connected to the microcomputer circuit 50 area memory 51 for storing a control program such as an optometric program,as well as a memory 52 for storing objective value data and the like.The microcomputer circuit 50 converts the switch signal to various dataon the basis of the control program stored in the memory 51, andcontrols the screen of the display 30 through a display circuit 53. Inaddition, the converted signal is inputted to a microcomputer circuit 55of the relay unit 6. The microcomputer circuit 55 supplies data onrefractive power and the movement of lens units 10 to thesubjective-type refractive-power measuring device 2 and supplies data onthe target (chart) to the target (chart) presenting device 4.

A microcomputer circuit 60 of the subjective-type refractive-powermeasuring device 2 which has received the data on the refractive powerdrives motors 62 via drive circuits 61 to rotate a weak spherical disk63, a strong spherical disk 64, an auxiliary lens disk 65, across-cylinder disk 66, and the like, thereby disposing predeterminedoptical systems in the test windows. In addition, the microcomputercircuit 60, upon receiving signals concerning the sliding and flappingof the lens units 10, drives the drive motors 204 and 207.

A microcomputer circuit 70 of the target (chart) presenting device 4which has received the data on the target (chart) lights up a lamp 72via a drive circuit 71, drives two motors 74 via two drive circuit 73,and rotates a target (chart) disk 75 with a target (chart) depictedthereon and a mask disk 76, respectively, thereby projecting apredetermined test target (chart) onto an unillustrated screen placed infront of the eye being examined.

The objective-type ocular refractive-power measuring device 3 and a lensmeter 9 are connected to the microcomputer circuit 55, and measurementdata sent to the microcomputer circuit 55 is stored in a memory 56. Whena read command signal is inputted from the microcomputer circuit 50 onthe controller 5 side to the microcomputer circuit 55, the microcomputercircuit 55 reads the designated measurement data from the memory 56 andtransfers the same to the controller 5.

Numeral 57 denotes a printer for outputting the results of measurement,and 58 denotes a drive circuit thereof.

A description will be given of the operation of the apparatus having theabove-described configuration. Here, a description will be given of theoperation using an optometric program in which test items and a testprocedure have been set in advance (see FIG. 5).

At the time of examination, when parameters are set and information onan inquiry after the subject is entered, a menu switch 32a of the groupof setting changeover switches 32 is pressed. A set menu screen such asthe one shown in FIG. 6 is displayed on the display 30. A cursor (theshaded part in FIG. 6) can be moved by move switches 32b and 32c of thegroup of switches 32, and item of display which the cursor is moved canbe selected by an execute switch 32d.

If an "inquiry" menu is selected, an inquiry screen is displayed on thedisplay 30. As items of inquiry, those for entering the purpose ofmaking spectacles, age, type of sex, occupation, hobbies, history ofspectacles, history of contact lenses, and the like have been prepared.When selecting an item, a cursor is moved by means of the move switches32b and 32, and an item is selected by the execute switch 32d. When anitem for entering age, for example, is selected, the screen is changedover to an age input screen such as the one shown in FIG. 7. The age isentered by making a change by rotating a dial switch.

<Execution of Optometric Program>

Upon completion of the setting of necessary parameters and the entry ofinquiry information, the start switch 35 is pressed to execute theoptometric program. A message prompting the entry of measurement data bymeans of the objective-type ocular refractive-power measuring device 3is displayed on the display 30.

<Input of Objective Value Data>

Various objective value data such as S (SPH: power of the spherical lens(spherical power)), C (CYL: power of astigmatism (cylindrical power)), A(AXIS: angle of astigmatic axis (cylindrical axis)), and the like whichare obtained from the objective-type ocular refractive-power measuringdevice 3 are stored in the memory 56 via the microcomputer circuit 55 ofthe relay unit 6 by pressing the print switch of the objective-typeocular refractive-power measuring device 3. Subsequently, if the datainput switch 39 of the controller 5 is pressed, and the objective switchof the group of input-data designating switches 38 is then pressed, theobjective value data stored in the memory 56 are transferred to andstored in an objective value memory area of the memory 52 on thecontroller 5 side.

It should be noted that the input of the objective value data may beeffected manually by the operation of the group of mode-changedesignating switches 37, the dial switch 42, or the like apart from thedata transfer through communication.

Upon completion of the input of the objective value data, the apparatusdetermines whether or not the case under examination is a hyperopiccase. As to whether or not the case is a hyperopic case, the case isdetermined to be a hyperopic case when, for instance, a sphericalequivalent value (SE value) is a plus or a minus of a weak power such as-0.50 D. If the spherical equivalent value in objective measurement is aminus of a weak power in objective measurement, there are cases wheremeasurement is made in a state in which accommodative power isfunctioning, so that there is a need to hold a doubt that the case mayactually be a hyperopic case. In a hyperopic case, a message to theeffect that "Exercise caution to intervention by accommodation,particularly in the case of a young subject" is displayed for a numberof seconds. The reason for this is that if a hyperopic eye is intervenedby the accommodative power, there are cases where it is impossible toobtain accurate test results, so that more caution should be exercisedin the prescription of spectacles. The accommodative power is liable tofunction in the hyperopia of a young subject (about 15 years of age oryounger), in which case it is difficult to perform optometry accurately,and there are cases where it is desirable to conduct the test afterhaving a measure, such as the administration of a cycloplegic agent,provided by an ophthalmologist. Such a display makes it possible toprompt even an unskilled examiner to exercise caution, so that theexaminer is capable of readily providing measures necessary for futuretests (e.g., setting the amount of fogging to a level greater thannormal, extending a fogging period, and referral to an ophthomologist).

Incidentally, values for determining whether or not the case is ahyperopic case (in terms of the SE value, -0.25 D, -0.50 D, -0.75 D,etc.) can be set in advance in the setting of parameters.

In addition, the display to the effect of prompting the exercise ofcaution to the intervention by accommodation may be effected only whenthe age of the subject which has been entered is a predetermined age orbelow. In this case, whether to provide a display depending on theinputted age is set in advance in the setting of parameters. Further, anarrangement is also provided that the predetermined age can be set inadvance.

<Testing of Unaided Visual Acuity>

Upon completion of the input of objective value data, the objectivevalue data is automatically copied to a subjective value memory area,and the last copied data (subjective value data=objective value data) isdisplayed in left and right display portions 81 in an example of thescreen shown in FIG. 8. Subsequently, in terms of the test item, theoperation proceeds to the testing of unaided visual acuity. The displayscreen of the display 30 is set to a mode in which the value of unaidedvisual acuity of the right eye can be automatically entered, and thesubjective value data shifts to the left and right display portions 81.FIG. 8 is an example of display at this time. A present test item isdisplayed in a central display portion, and entry can be made for ameasurement item which is reversely displayed.

This apparatus has the function of calculating a value of unaided visualacuity which is estimated on the basis of the objective value data, andwhen the testing of unaided visual acuity is started, an operationsignal is issued to the target (chart) presenting device 4 to present atest target (chart) having a calculated value of estimated vision. Anestimated value of unaided visual acuity is displayed in the VA columnof the central display portion 80, and a target (chart) pattern 83 whichis being presently presented is displayed in an operation explanationarea 82 below the central display portion 80. The examiner applies amask to the target (chart) by using switches 34a and 34b of the group ofmask switches 34 on the basis of response from the subject, obtains avalue of unaided visual acuity of the eye being measured by changing thepresented target (chart), and inputs the same. In this case, the testmay be conducted by causing the subject to hold an eye cover withoutdisposing the subjective-type refractive-power measuring device 2 infront of the eye being examined, or the test window of the measurementeye side may be opened with the other eye covered.

After the testing of the unaided visual acuity of the right eye isfinished, an L switch of the measurement-eye designating switch 41 ispressed so as to test the unaided visual acuity of the left eye in asimilar manner. At this time as well, if the objective value data of theleft eye is a hyperopic case, a display is given on the screen to thateffect. In addition, as a test target (chart) which is presented at thistime, one which is different from the one for the right eye isautomatically selected.

Subsequently, a binocular switch of the measurement-eye designatingswitch 41 is designated, and the testing of unaided binocular visualacuity is performed. A highest value of visual acuity between the rightand left eye is automatically displayed in the VA column of the centraldisplay portion 80, and the testing can be started from that value.

<Input of Spectacle Data>

After the unaided binocular visual acuity has been inputted, the advanceswitch 36 is pressed to proceed to an ensuing test item. A message tothe effect that the presence or absence of spectacles (including contactlenses) should be confirmed is displayed on the display 30, and thedesignation of switch operation based on the presence or absence ofspectacles is displayed below the screen. If the function switch 45 forthe presence of spectacles is pressed in compliance with theinstruction, the mode is changed over to one in which the spectaclepower data can be entered. In the same way as the objective value data,the entered spectacle power data is transferred from the lens meter 9 tothe memory 56 and is stored therein, and if the input switch 39 and aspectacle switch of the group of switches 38 are pressed, the spectaclepower data is stored in a former-spectacle memory area of the memory 52(or may be manually entered by operating the dial switch 42 or thelike).

It should be noted that in a case where the powers of spectacles havebeen entered in advance prior to the start of testing, this stage ofinput of spectacle data is omitted.

<Testing of Spectacled Visual Acuity>

After the spectacle power data has been inputted, the screen of thedisplay 30 is changed over to a mode of testing for confirmation of thespectacled visual acuity of the right eye. Since optical systemscorresponding to the spectacle power data are disposed in the testwindows of the subjective-type refractive-power measuring device 2, thetest may be conducted by disposing the subjective-type refractive-powermeasuring device 2 in front of the subject's eyes. An estimated visualacuity value based on the residual power due to the difference betweenthe objective value data and the spectacle power data is displayed inthe VA column for the right eye in the central display portion 80, and asignal is issued to the target (chart) presenting device 4 to present atest target (chart) having that visual acuity value. A visual acuityvalue is obtained by changing over the presented target (chart) by meansof the switches 34a and 34b on the basis of the response from thesubject, and that value is inputted. If the test is conducted for theleft eye and both eyes in a similar manner, visual acuity values areinputted in the same way as in the case of the testing of unaided visualacuity.

<Confirmation of Visual Acuity Based on Objective Value Data>

Then, if the advance switch 36 is pressed, the operation proceeds to thetesting for confirmation of objective visual acuity for confirming theappropriateness of the objective value data. Optical systemscorresponding to the objective value data are initially set in the testwindows of the lens units 10, so that the state is set for allowing theright eye to be examined. The examiner disposes the subjective-typerefractive-power measuring device 2 in front of the subject's eyes. Fromthe target (chart) presenting device 4, test targets (charts) providedin a set of targets (charts) with visual acuity values ranging from 0.5to 0.7 are presented with vertical masks applied thereto. The testingfor confirmation of the subjective visual acuity in the prescription ofspectacles is carried out primarily for the purpose of confirming thereliability of objective value data and the presence of any abnormalityin the visual function, such as amblyopia, in the eye being examined.Therefore, a target (chart) having a minimum visual acuity value of 0.5,which serves as a reference for this confirmation, is initiallypresented in this apparatus. If the eye being examined is unable todiscern the target (chart) with the visual acuity value of 0.5,necessary measures are taken such as the reconducting of objectivemeasurement and close examination.

<Test for Determining Values of Monocular Complete Correction>

If the presented target (chart) is legible in the test for confirmationof objective visual acuity, the advance switch 36 is pressed to proceedto the ensuing test for determining values of monocular completecorrection. This test is effected in the order of a first R/G(red/green) test which is generally carried out before the testing ofastigmatism, an astigmatic- (cylindrical-) axis adjustment test, anastigmatic- (cylindrical-) power adjustment test, a second R/G test forobtaining maximum visual acuity while preventing over correction, andoptometry. However, this apparatus has a program for changing the testprocedure on the basis of the C value of the inputted objective valuedata (or the C value of the spectacle power data may be used) (see FIG.9). Depending on whether the C value of the objective value data is lessthan or equal to a first predetermined reference value (CYL=0), the testprocedure proceeds as described below.

[A: When CYL=0]

A message is displayed on the screen of the display 30 to the effectthat confirmation is to be made as to whether or not to effectconfirmation of astigmatism, and an operational instruction, "YES" or"NO," for responding to it is displayed in a lower portion of thescreen. The examiner makes entry by pressing a relevant function switch45 which corresponds to the operational instruction.

[A-1] In a case where the confirmation of astigmatism is not to becarried out, if the "NO" switch is pressed, the first R/G test, theastigmatic- (cylindrical-) axis adjustment test, and the astigmatic-(cylindrical-) power adjustment test are omitted, and the test stepproceeds to the second R/G test. If astigmatism does not appear in theobjective value data, astigmatism is frequently not detected in thesubjective tests as well. Therefore, it is possible to enhance thetesting efficiency by omitting useless test items without conductingmany troublesome switch operations.

[A-2] When the presence of astigmatism is suspected or accuracy is to beensured, the confirmation of astigmatism is carried out. If the "YES"switch is pressed, the operation proceeds to the step of the first R/Gtest. In the test window of the subjective-type refractive-powermeasuring device 2, fogging is provided by imparting a spherical powerof +0.50 D to the optical system set at an initial value so as toeliminate intervention by the accommodation of the eye being measured.The amount of fogging is displayed on the display screen. Apredetermined red-green target (chart) is presented from the target(chart) presenting device 4, and Be the controller 5 is set in a mode inwhich the spherical power can be changed. The examiner adjusts thespherical power by operating the dial switch 42 on the basis of thesubject's response on appearances, such that the letters in red andgreen in the red-green target (chart) can be viewed at the same power orthe green side can be viewed slightly better, by way of an attempt tolocate the circle of least confusion in the vicinity of the retina.

Upon completion of the adjustment of the spherical power in the firstR/G test, if the advance switch 36 is pressed, the operation proceeds toa test for confirmation of the power by means of a cross-cylinder lens(hereafter, XC lens) at an astigmatic axis=0°. A spot-group target(chart) is presented as the test target (chart), and the controller 5 isset in a mode in which the power of astigmatism can be changed. The XClens is set in the test window of the subjective-type refractive-powermeasuring device 2 with a minus axial angle set at 90°. The examinerinverts the XC lens by means of the changeover switches 43a (this switchsets the minus axis to 90°) and 43b (this switch sets the minus axis to180°) so as to allow the subject to confirm the difference in theappearance. Then, the dial switch 42 is rotated toward the side forwhich a response that better vision is obtained has been given, so as toobtain a change in the C value. When the pressing of the switch 43agives better vision, if the dial switch 42 is rotated counterclockwiseby one click, the C value becomes -0.25 D, while the A value becomes90°. Conversely, when the pressing of the switch 43b gives bettervision, if the dial switch 42 is rotated clockwise by one click, the Cvalue becomes -0.25 D, while the A value becomes 0°. Subsequently, theoperation proceeds to the step for the case where CYL≠0.

Here, when there is no change in the C value, the advance switch 36 ispressed to proceed to a test for confirmation of the power with theastigmatic (cylindrical) axis set to 45°. The minus axial angle of theXC lens is set to 135°. This is effected to confirm the presence ofastigmatism in an oblique direction. Similarly, the examiner inverts theXC lens to allow the subject to confirm the difference in theappearance. In this test as well, if there is no change in the C value,it can be determined that astigmatism is not present, and it is assumedthat close examination of astigmatism is unnecessary, so that theoperation proceeds to the second R/G test. If there is a change, theoperation proceeds to the step for the case where CYL≠0.

[B: When CYL≠0]

As a result of determination by the apparatus, the operation proceeds tothe step of the first R/G test. In the same way as described above, theexaminer adjusts the spherical power and makes an attempt to locate thecircle of least confusion in the vicinity of the retina.

Upon completion of the first R/G test, if the advance switch 36 ispressed, the test procedure is altered as described below as a result ofdetermination by the apparatus as to whether or not the C value of theobjective value data is greater than or equal to a second predeterminedreference value (hereafter, this value will be set at -0.50 D). Itshould be noted that the C value which is "greater than or equal to" thesecond predetermined reference value is meant to include both a minusreading and a plus reading, and refers to one whose absolute value isgreater.

[B-1] If the C value is greater than or equal to -0.50 D, the operationproceeds in the order of the astigmatic- (cylindrical-) axis adjustmenttest and the astigmatic- (cylindrical-) power adjustment test.

In the astigmatic- (cylindrical-) axis adjustment test, the controller 5is set in a mode in which the astigmatic (cylindrical) axis can bechanged, and the XC lens is set in the test window of thesubjective-type refractive-power measuring device 2 in a state in whichthe axis of inversion is adjusted to the astigmatic (cylindrical) axisof the objective value data. A spot-group target (chart) is presented asthe test target (chart). The examiner inverts the XC lens by means ofthe changeover switches 43a and 43b to allow the subject to confirm thedifference in the appearance, and moves the axis of inversion until thetest target (chart) is viewed substantially uniformly before and afterthe inversion. In the apparatus of this embodiment, the axis ofinversion is moved in a predetermined angular step by rotating the dialswitch 42 toward the switch 43a or 43b side for which a response thatbetter vision is obtained has been given, thereby making it possible toobtain an angle of astigmatic (cylindrical) axis.

Concerning the movement of the axis of inversion of the XC lens at thistime, the apparatus has a program for changing the step of the adjustingangle of the astigmatic (cylindrical) axis depending on whether or notthe C value of the objective value data (or the C value of the spectaclepower data) is greater than or equal to a third predetermined referencevalue. For example, when the C value of the objective value data isgreater than or equal to -1.25 D, the axis of inversion is moved insteps of 1°, and when it is less than -1.25 D, the axis of inversion ismoved in steps of 5°. In cases where the C value is relatively small,the axis is not detected stably even if the axis is detected in fineangular steps, so that it is of little significance to do so. On theother hand, if the C value is large, there are many cases where the axiscan be detected accurately at fine angular steps of 1°. Therefore, sincethe apparatus automatically sets this change on the basis of the C valueof the objective value data, the examiner is dispensed from altering thesetting for each C value during the test, and even an unskilled examineris able to proceed with the test readily and efficiently. Incidentally,the examiner is able to set in advance the criteria of determination bythe apparatus. This is effected by operating the group of settingchangeover switches 32 among the items of parameter setting in the menuscreen. Further, depending on the examiner's policy of examination, 5°or 1° may be constantly fixed without making a change based on the Cvalue, or may be changed over in the course of the examination.

Upon completion of the astigmatic- (cylindrical-) axis adjustment test,if the advance switch 36 is pressed, the operation proceeds to theastigmatic- (cylindrical-) power adjustment test. The plus axis of theXC lens is set in the test window of the subjective-typerefractive-power measuring device 2 in conformity with the obtainedastigmatic (cylindrical) axis. The examiner obtains the power ofastigmatism (cylinder) by making an adjustment by increasing ordecreasing the C value depending on the appearance before and after theinversion of the XC lens.

Upon completion of the astigmatic- (cylindrical-) power adjustment test,if the advance switch 36 is pressed, the apparatus makes a comparisonbetween the obtained power of astigmatism (cylinder) and that of theobjective value data. In cases where the variation of the power betweenthem is less than or equal to 0.25 D, the obtained values are determinedas the astigmatic (cylindrical) axis and the power of astigmatism(cylinder). However, in cases where the variation of the power isgreater than or equal to 0.50 D, the operation returns to theastigmatic- (cylindrical-) power adjustment test. The reason for this isthat such a large change in the power that causes the power ofastigmatism (cylinder) to change by two steps or more has a largepossibility of causing a variation in the axis. If there is no variationwith respect to the value of the astigmatic (cylindrical) axis obtainedin the previous astigmatic- (cylindrical-) axis adjustment test, theobtained values are determined as the power and the axis of astigmatism(cylinder), and the operation proceeds to the second R/G test. If thereis a variation, the operation returns to the astigmatic- (cylindrical-)power adjustment test.

[B-2] If the C value is less than -0.50 D (i.e. it is -0.25 D), theastigmatic- (cylindrical-) power adjustment test is conducted prior tothe astigmatic- (cylindrical-) axis adjustment test. The reason for thisis because there is a possibility that the power of astigmatism(cylinder) is 0 in the test for detecting the power of astigmatism(cylinder), and because if the power of astigmatism (cylinder) is 0, theastigmatic- (cylindrical-) axis test is unnecessary. (If the test fordetecting the axis is conducted first, and the power of astigmatism(cylinder) is 0, the test of the axis is wasted.)

If CYL=0 as a result of this test, the test for detecting the axis isunnecessary. Hence, the advance switch is pressed to proceed to thesecond R/G test by omitting the detection of the astigmatic(cylindrical) axis (by providing a setting such that AXIS=0). If the Cvalue is greater than or equal to -0.25 D, the astigmatic-(cylindrical-) axis test is subsequently conducted, and the power andthe axis of astigmatism (cylinder) are determined.

When the adjustment of the power and the axis of astigmatism (cylinder)is completed and their values are determined as described above, theoperation proceeds to the second R/G test. A spherical power of +0.50 Dis imparted to the test window of the subjective-type refractive-powermeasuring device 2 to provide fogging. The amount of fogging isdisplayed on the display screen. A predetermined red-green target(chart) is presented as the target (chart) from the target (chart)presenting device 4. Since the controller 5 is set in a mode in whichthe spherical power can be changed, the examiner adjusts the sphericalpower by operating the dial switch 42 on the basis of the subject'sresponse on the appearance, such that the letters in red and green canbe viewed at the same power or the red side can be viewed slightlybetter.

Upon completion of the second R/G test, if the advance switch 36 ispressed, the operation proceeds to optometry. Test targets (charts)provided in a set of targets (charts) having a visual acuity value of1.0 are presented with horizontal masks applied thereto. When thehighest visual acuity is determined, the examiner adjusts the sphericalpower, and sets a power which gives the highest visual acuity which ismaximally on the plus side, so as to determine completely correctedvalues for one eye.

When the perfect correction values for one eye have been determined, theadvance switch 36 is pressed to proceed to the test for obtainingperfect correction values for the other eye. If a maximum visual acuityvalue of the eye being examined which is inputted at this time is lessthan 0.7, a message is displayed on the screen to the effect thatreadjustment of S, C, and A is prompted by confirming the visual acuityby a pin-hole test. An operational instruction, "YES" or "NO," forresponding to it is displayed in the lower portion of the screen. If thepin-hole test is required, a designation is given by means of thefunction switch 45 corresponding to the operational instruction(alternatively, the message to the effect that the pin-hole test isprompted may be simply displayed for a number of seconds, and thesubsequent operation may be left to the discretion of the examiner). If"YES" is designated, a pin-hole plate is set in the test window of thesubjective-type refractive-power measuring device 2. The-eye beingmeasured is allowed to view the optometric target (chart) through thepin hole, and confirmation is made as to whether or not visual acuityhas improved. Since an operational instruction, "YES" or "NO," forinquiring whether or not visual acuity has improved is displayed in thelower portion of the screen, so that the function switch 45 is pressedin compliance with the operational instruction.

If "NO" is pressed, a message is displayed to the effect that closeexamination of such as the cornea and the retina is required. In thepin-hole test as well, in a case where there is no change in visualacuity, not only a correction error but also other factors ofabnormality in such as the cornea, the retina, and optic nerves areconceivable. As a result, the examiner adopts a necessary measure suchas close examination.

If "YES" is inputted, the test item returns to the test for confirmationof visual acuity on the basis of objective value data, which is aninitial stage of the subjective examination. When visual acuity improvesin the pin-hole test, there is a possibility that perfect correction wasinsufficient, so that the perfect correction test is conducted again.

If 0.7 is obtained as a highest visual acuity value of one eye, theadvance switch 36 is pressed to proceed to the test for obtainingperfect correction values for the other eye. The examiner obtainsperfect correction values for the other eye in a similar manner.

<Binocular Balance Test>

When perfect correction values are obtained for each eye, the advanceswitch 36 is pressed to proceed to a binocular balance test. Polarizingplates are disposed in the test windows of the subjective-typerefractive-power measuring device 2, and a spherical power in an amountof fogging for setting the value of perfect correction visual acuity to0.8 or thereabouts is imparted to provide fogging. The amount of foggingis displayed on the display screen. In addition, values obtained in themonocular perfect correction are copied in the central display portion80 on the screen, and the operation is set in a mode in which thespherical powers of both eyes can be inputted. Values obtained in theperfect correction, including visual acuity values, are transcribed tothe left and right display portions 81. Binocular balance targets(charts) are presented as the test targets (charts).

The subject is allowed to confirm the difference in appearances in theleft and the right eyes using the binocular balance targets (charts). Ifthere is a difference, the eye which give better vision is designated bymeans of the R switch or the L switch of the measurement-eye designatingswitch 41, and balance correction for adding S+0.25 D is effected. Atthis time, unaided visual acuity values and visual acuity values basedon the former spectacles are displayed in the lower portion of thecentral display portion 80. If vision by the eyes which have beencorrected by the balance correction is less sharp, reference is made tothis information, and priority is placed on the visual acuity valueswhich are based on the former spectacles and give better vision (in thecase of a subject wearing the spectacles for the first time, priority isplaced on the unaided visual acuity values which give better vision). Inaddition, since there are cases where the determination of balancecorrection is made by the dominant eye, it is convenient to input andstore dominant eye information in advance in the memory, and display thesame on the screen.

Thus, values of binocular perfect correction are obtained (in thisspecification, those perfect correction values which are obtained afterconducting the binocular balance test are referred to as the values ofbinocular perfect correction).

<Test for Confirming Stereoscopic Vision>

Upon completion of adjustment of the binocular balance, the advanceswitch 36 is pressed to proceed to the test for confirming stereoscopicvision. The fogging with the spherical powers applied during thebinocular balance test is removed from the test windows of thesubjective-type refractive-power measuring device 2, and a messageinforming the examiner of the effect that fogging has been removed isdisplayed in the lower portion of the central display portion 80. Thus,the apparatus automatically cancels the fogging by an input signal fromthe advance switch 36, and displays to that effect, so that the examineris able to conduct an ensuing test with appropriate optical systemswithout needing to remember the cancellation of the fogging.

In the test of stereoscopic vision, stereoscopic targets (charts) arepresented. Instructions for operation (1', 2', 4', 10', NG) forinputting stereoscopic parallax are displayed in the lower portion ofthe screen. Depending on to what extent the stereoscopic parallax can beconfirmed by the subject, the examiner presses a function switchcorresponding to the operational instruction, and enters the same. Thisresult is printed during printout.

<Adjustment of Correction Powers for Far Use--(1) Automatic Adjustment>

Upon completion of the test for confirming stereoscopic vision, theoperation proceeds to adjustment of correction powers for far use fordetermining rough powers serving as prescription values for far use.This apparatus has an automatic adjustment program whereby, if thevalues of binocular perfect correction obtained as described above andspectacle values are available, rough powers serving as prescriptionvalues which are estimated to be optimal for the subject areautomatically calculated on the basis of that data. When the optometricprogram is in progress, an input signal from the advance switch 36executes the automatic adjustment program, and rough powers serving asprescription values which are calculated are displayed on the centraldisplay portion 80.

Hereafter, referring to flowcharts shown in FIGS. 10 to 15, adescription will be given of this automatic adjustment program. Itshould be noted that the term "a stronger eye" used in the descriptionthat follows refers to whichever has a greater absolute value in termsof the power of each of the S value and the C value between the perfectcorrected both eyes. Meanwhile, the term "a weaker eye" refers to theopposite of the same. In addition, a minus reading is adopted forastigmatism (cylinder) (C value).

First, the apparatus determines the presence or absence of astigmatism(cylinder) on the basis of the values of binocular perfect correction(Step 1-1). If astigmatism (cylinder) is present, a determination ismade as to whether or not astigmatism (cylinder) is oblique astigmatism(cylinder) (AXIS: 15° to 75° or 105° to 165°) (Step 1-2). Subsequently,on the basis of the S values of both eyes a determination is made as tohyperopia (both eyes are plus, or one eye is plus and the other eye is0) or myopia (both eyes are minus, or one eye is minus and the other eyeis 0) (Steps 1-3 to 1-5), so that adjusted powers can be calculated byeffecting the processing of one of ensuing power adjustments A to F.When it is impossible to distinguish between hyperopia and myopia (the Svalue of one eye is plus, and the S value of the other eye is minus),the power adjustment is not effected, and a message is displayed to theeffect that the examiner is to make an adjustment.

[Automatic Adjustment A: In the Case of Hyperopia Without Astigmatism(Cylinder)]

On the basis of the presence or absence of the input of spectacle powerdata (presence or absence of a history of spectacles), the apparatusdetermines whether or not the subject wears the spectacles for the firsttime (Step A-1).

[A-1] If the subject wears the spectacles for the first time, thedifference between the S values of the left and right eyes is thencompared with a reference value (Step A-2). If the difference betweenthe S values of the left and right eyes is within a predetermined powerdifference (hereafter, a description will be given under the assumptionthat the difference in the S value or the C value between the left andright eyes is to be adjusted to within 0.75 D), the values of binocularperfect correction are used as they are as adjusted powers. If thedifference in the S value between the left and right eyes exceeds 0.75D, the S value of the stronger eye is set to a value in which +0.75 D isadded to the S value of the weaker eye (Step A-3).

[A-2] If the subject does not wear the spectacles for the first time,the difference in the S value between the left and right eyes iscompared with the reference value (Step A-4). If the difference betweenthe left and right eyes exceeds 0.75 D, the S value of the stronger eyeis set to whichever value having a greater absolute value between avalue in which +0.75 D is added to the S value of the weaker eye and avalue in which a predetermined power (in the case of a hyperopia, +0.75D hereafter) is added to the S value of the same side of the formerspectacles, such that the value does not exceed the relevant one of thevalues of binocular perfect correction (Step A-5).

[Automatic Adjustment B: In the Case of Myopia Without Astigmatism(Cylinder)]

A determination is made as to whether or not the subject wears thespectacles for the first time (Step B-1).

[B-1] If the subject wears the spectacles for the first time, correctionprocessing is first carried out in which a correction amount ΔS1 isobtained by calculation in Table A in FIG. 16 by using as a referencethe S value of the weaker eye obtained in binocular perfect correction,and the correction amount ΔS1 is subtracted from each of the S values ofbinocular perfect correction for both eyes (hereafter, this processingwill be referred to as correction processing A1) (Step B-2). Next, thedifference between the left and right eyes after correction processingis compared with the reference value (Step B-3), and if the differenceexceeds 0.75 D, the S value of the stronger eye is set to a value inwhich -0.75 D is added to the S value of the weaker eye (Step B-4).

[B-2] If the subject does not wear the spectacles for the first time,correction processing is carried out in which a correction amount ΔS2 isobtained by calculation in Table B in FIG. 16 by using as a reference asmaller one of the differences between the former spectacle value andthe value of binocular perfect correction in left and right S values,and the correction amount ΔS2 is subtracted from each of the S values ofbinocular perfect correction for both eyes (hereafter, this processingwill be referred to as correction processing B1) (Step B-5). Next, thedifference in the S value between the left and right eyes aftercorrection processing is compared with the reference value (Step B-6),and if the difference exceeds 0.75 D, the S value of the stronger eye isset to whichever value having a greater absolute value between a valuein which -0.75 D is added to the corrected S value of the weaker eye anda value in which a predetermined power (in the case of a hyperopia,-0.75 D hereafter) is added to the S value of the same side of theformer spectacles, such that the value does not exceed the relevant oneof the values of binocular perfect correction (Step B-7).

[Automatic Adjustment C: In the Case of Hyperopia Having Astigmatism(Cylinder) Which is Not Oblique Astigmatism (Cylinder)]

A determination is made as to whether or not the subject wears thespectacles for the first time (Step C-1).

[C-1] If the subject wears the spectacles for the first time, correctionprocessing is first carried out in which a correction amount ΔC1 isobtained by calculation in Table C in FIG. 16 by using as a referencethe C value of the weaker eye, and the correction amount ΔC1 issubtracted from each of the C values of binocular perfect correction forboth eyes (hereafter, this processing will be referred to as correctionprocessing C1) (Step C-2). Then, the S values of both eyes are each setto a value in which half of the correction amount ΔC1 is added to thevalue of binocular perfect correction to obtain a spherical equivalentvalue (Step C-3). Subsequently, the difference between the obtained Svalues of the left and right eyes is compared with the reference value(Step C-4), and if the difference exceeds 0.75 D, the S value of thestronger eye is set to a value in which +0.75 D is added to the S valueof the weaker eye (Step C-5). Next, the difference in the C valuebetween the left and right eyes after the correction processing C1 iscompared with the reference value (Step C-6), and if the differenceexceeds 0.75 D, the C value of the stronger eye is set to a value inwhich -0.75 D is added to the C value of the weaker eye (Step C-7).

[C-2] In a case where the subject does not wear the spectacles for thefirst time, first, if astigmatism (cylinder) is not present on the basisof the determination of the presence or absence of astigmatism(cylinder) in the former spectacle values (Step C-8), the same poweradjustment as in the case of the initial wearing is performed (Steps C-2to C-7). If astigmatism (cylinder) is present, correction processing iscarried out in which a correction amount ΔC2 is obtained by calculationin Table D in FIG. 16 by using as a reference a smaller one of thedifferences between the former spectacle value and the value ofbinocular perfect correction in left and right C values, and thecorrection amount ΔC2 is subtracted from each of the C values ofbinocular perfect correction for both eyes (hereafter, this processingwill be referred to as correction processing D1) (Step C-9). Then, the Svalues of both eyes are each set to a value in which half of thecorrection amount ΔC2 is added to the value of binocular perfectcorrection to obtain a spherical equivalent value (Step C-10).Subsequently, the difference between the obtained S values of the leftand right eyes is compared with the reference value (Step C-11), and ifthe difference exceeds 0.75 D, the S value of the stronger eye is set towhichever value having a greater absolute value between a value in which+0.75 D is added to the S value of the weaker eye made sphericallyequivalent and a value in which +0.75 D is added to the S value of thesame side of the former spectacles, such that the value does not exceedthe relevant one of the values of binocular perfect correction (StepC-12). Next, if the difference in the C value between the left and righteyes after the correction processing D1 exceeds 0.75 D (Step C-13), theC value of the stronger eye is set to whichever value having a greaterabsolute value between a value in which -0.75 D is added to the C valueof the weaker eye and a value in which -0.75 D is added to the C valueof the same side of the former spectacles, such that the value does notexceed the relevant one of the values of binocular perfect correction(Step C-14). [Automatic Adjustment D: In the Case of Myopia HavingAstigmatism (Cylinder) Which is Not Oblique Astigmatism (Cylinder)]

A determination is made as to whether or not the subject wears thespectacles for the first time (Step D-1). [D-1] If the subject wears thespectacles for the first time, the correction processing C1 is carriedout (Step D-2), and the correction processing A1 is carried out (StepD-3). Subsequently, the difference between the obtained S values of theleft and right eyes is compared with the reference value (Step D-4), andif the difference exceeds 0.75 D, the S value of the stronger eye is setto a value in which -0.75 D is added to the S value of the weaker eye(Step D-5). Next, the difference in the C value between the left andright eyes after the correction processing C1 is compared with thereference value (Step D-6), and if the difference exceeds 0.75 D, the Cvalue of the stronger eye is set to a value in which -0.75 D is added tothe C value of the weaker eye (Step D-7).

[D-2] In a case where the subject does not wear the spectacles for thefirst time, first, a determination is made as to the presence or absenceof astigmatism in the former spectacle values (Step D-8). If astigmatism(cylinder) is present, the correction processing D1 is effected (StepD-9). Then, the correction processing B1 is carried out (Step D-10).Subsequently, the difference between the obtained S values of the leftand right eyes is compared with the reference value (Step D-11), and ifthe difference exceeds 0.75 D, the S value of the stronger eye is set towhichever value having a greater absolute value between a value in which-0.75 D is added to the S value of the weaker eye and a value in which-0.75 D is added to the S value of the same side of the formerspectacles, such that the value does not exceed the relevant one of thevalues of binocular perfect correction (Step D-12). Next, the differencein the C value between the left and right eyes after the correctionprocessing D1 is compared with the reference value (Step D-13), and ifthe difference exceeds 0.75 D (Step D-13), the C value of the strongereye is set to whichever value having a greater absolute value between avalue in which -0.75 D is added to the C value of the weaker eye and avalue in which -0.75 D is added to the C value of the same side of theformer spectacles, such that the value does not exceed the relevant oneof the values of binocular perfect correction (Step D-14).

If astigmatism (cylinder) is not present in the determination on thepresence or absence of astigmatism (cylinder) of the former spectaclevalues, the correction processing C1 and the correction processing B1are carried out (Steps D-15 and D-16). Subsequently, the differencebetween the obtained S values of the left and right eyes is comparedwith the reference value (Step D-17), and if the difference exceeds 0.75D, the S value of the stronger eye is set to whichever value having agreater absolute value between a value in which -0.75 D is added to theS value of the weaker eye and a value in which -0.75 D is added to the Svalue of the same side of the former spectacles, such that the valuedoes not exceed the relevant one of the values of binocular perfectcorrection (Step D-18). Next, if the difference in the C value betweenthe left and right eyes after the correction processing C1 exceeds 0.75D, the C value of the stronger eye is set to a value in which -0.75 D isadded to the C value of the weaker eye (Steps D-19 and D-20).

[Automatic Adjustment E: In the Case of Hyperopia Having ObliqueAstigmatism]

The apparatus determines whether or not the subject wears the spectaclesfor the first time (Step E-1).

[E-1] If the subject wears the spectacles for the first time, adetermination is made as to whether or not both C values of the left andright eyes are less than or equal to -0.50 D (hereafter, the C valuebeing less than or equal to -0.50 D refers to a smaller power, i.e.,-0.25 D or -0.50 D) (Step E-2). In the case of astigmatism, if the Cvalue is small, it is in many cases more desirable not to effect thecorrection of astigmatism (cylinder) for the subject. Therefore, if bothC values of the left and right eyes are less than or equal to -0.50 D,it is assumed that astigmatism (cylinder) is negligible, so that the Cvalues=0, and the S values for left and right are each set to a value inwhich half of the C value is added to the S value to obtain a sphericalequivalent value (Step E-3). Subsequently, the difference between theobtained S values of the left and right eyes is compared with thereference value (Step E-4), and if the difference exceeds 0.75 D, the Svalue of the stronger eye is set to a value in which +0.75 D is added tothe S value of the weaker eye (Step E-5).

In the determination (Step E-2) as to whether or not the C values areless than or equal to -0.50 D, if at least one of the left and right Cvalues exceeds -0.50 D, the correction processing C1 is carried out(Step E-6), and the S values for left and right are each set to a valuein which half of the correction amount ΔC1 is added to the value ofbinocular perfect correction to obtain a spherical equivalent value(Step E-7). Subsequently, if the difference between the obtained Svalues of the left and right eyes exceeds 0.75 D, the S value of thestronger eye is set to a value in which +0.75 D is added to the S valueof the weaker eye (Steps E-8 and E-9). Next, if the difference in the Cvalue between the left and right eyes after the correction processing C1exceeds 0.75 D, the C value of the stronger eye is set to a value inwhich -0.75 D is added to the C value of the weaker eye (Steps E-10 andE-11).

[E-2] If the subject does not wear the spectacles for the first time, adetermination is made as to whether or not both C values of the left andright eyes are less than or equal to -0.50 D (Step E-12). Then, adetermination is made as to whether or not the respective formerspectacles have astigmatism (cylinder), respectively (Steps E-13 andE-14).

If both C values of binocular perfect correction are within -0.50 D, andthe former spectacles do not have astigmatism (cylinder), a setting isprovided such that the C values=0, and the S values for left and rightare each set to a value in which half of the C value is added to the Svalue to obtain a spherical equivalent value (Step E-15). Subsequently,the difference between the obtained S values of the left and right eyesis compared with the reference value (Step E-16), and if the differenceexceeds 0.75 D, the S value of the stronger eye is set to whichevervalue having a greater absolute value between a value in which +0.75 Dis added to the S value of the weaker eye made spherically equivalentand a value in which +0.75 D is added to the S value of the same side ofthe former spectacles, such that the value does not exceed the relevantone of the values of binocular perfect correction (Step E-17).

If the former spectacles have astigmatism (cylinder) in spite of the Cvalues of binocular perfect correction, processing similar to that inSteps C-9 to C-14 is carried out (Step E-18 to E-23).

If at least one of the left and right C values exceeds -0.50 D, and theformer spectacles do not have astigmatism (cylinder), the correctionprocessing C1 is carried out (Step E-24), and the S values of both eyesare each set to a value in which half of the correction amount ΔC1 isadded to the value of binocular perfect correction to obtain a sphericalequivalent value (Step E-25). Subsequently, the difference between theobtained S values of the left and right eyes is compared with thereference value (Step E-26), and if the difference exceeds 0.75 D,processing similar to that in Step C-12 is carried out (Step E-27).Next, the difference in the C value between the left and right eyesafter the correction processing C1 is compared with the reference value(Step E-28), and if the difference exceeds 0.75 D, the C value of thestronger eye is set to a value in which -0.75 D is added to the C valueof the weaker eye (Step E-29).

[Automatic Adjustment F: In the Case of Myopia Having ObliqueAstigmatism (Cylinder)]

The apparatus determines whether or not the subject wears the spectaclesfor the first time (Step F-1).

[F-1] If the subject wears the spectacles for the first time, adetermination is made as to whether or not both C values of the left andright eyes are less than or equal to -0.50 D (Step F-2). If both Cvalues are within -0.50 D, both C values are set such that C values=0(Step F-3). Then, the correction processing A1 is carried out for the Svalues (Step F-4). Subsequently, the difference between the obtained Svalues of the left and right eyes is compared with the reference value(Step F-5), and if the difference between the left and right eyesexceeds 0.75 D, the S value of the stronger eye is set to a value inwhich -0.75 D is added to the S value of the weaker eye (Step F-6).

In the determination (Step F-2) as to whether or not the C values areless than or equal to -0.50 D, if at least one of the left and right Cvalues exceeds -0.50 D, the correction processing C1 is carried out(Step F-7). Then, the correction processing A1 is carried out for the Svalues (Step F-8). Subsequently, the difference between the obtained Svalues of the left and right eyes is compared with the reference value(Step F-9), and if the difference between the left and right eyesexceeds 0.75 D, the S value of the stronger eye is set to a value inwhich -0.75 D is added to the S value of the weaker eye (Step F-10).Next, the difference in the C value between the left and right eyesafter the correction processing C1 is compared with the reference value(Step F-11), and if the difference exceeds 0.75 D, the C value of thestronger eye is set to a value in which -0.75 D is added to the C valueof the weaker eye (Steps F-12).

[F-2] If the subject does not wear the spectacles for the first time, adetermination is made as to whether or not both C values of the left andright eyes are less than or equal to -0.50 D (Step F-13). Then, adetermination is made as to whether or not the respective formerspectacles have astigmatism (cylinder) (C value), respectively (StepsF-14 and F-15).

If both C values of binocular perfect correction are within -0.50 D, andthe former spectacles do not have astigmatism (cylinder), a setting isprovided such that the C values=0 (F-16). Subsequently, the correctionprocessing B1 is carried out (Step F-17). Then, the difference betweenthe obtained S values of the left and right eyes is compared with thereference value (Step F-18), and if the difference between the left andright eyes exceeds 0.75 D, processing similar to that in Step B7 iscarried out for the S value of the stronger eye (Step F-19).

If the former spectacles have astigmatism (cylinder) in spite of the Cvalues of binocular perfect correction, processing similar to that inSteps D-9 to D-14 is carried out (Step F-20 to F-25).

If at least one of the left and right C values exceeds -0.50 D, and theformer spectacles do not have astigmatism (cylinder), the correctionprocessing C1 is carried out for the C values (Step F-26), and thecorrection processing B1 is carried out for the S values (Step F-27).Subsequently, the difference between the obtained S values of the leftand right eyes is compared with the reference value (Step F-28), and ifthe difference between the left and right eyes exceeds 0.75 D,processing similar to that in Step B-7 is carried out for the S value ofthe stronger eye (Step F-29). Next, the difference in the C valuebetween the left and right eyes after the correction processing C1 iscompared with the reference value (Step F-30), and if the differencebetween the left and right eyes exceeds 0.75 D, the C value of thestronger eye is set to a value in which -0.75 D is added to the C valueof the weaker eye (Step F-31).

In the above-described manner, when it is possible to distinguishbetween hyperopia and myopia, the apparatus effects the processing ofone of automatic adjustment A to F, and automatically calculates roughpowers serving as prescription values.

It should be noted that although, in the above-described automaticadjustment program, as for the adjustment amount for adjusting the Svalue or the C value of the stronger eye, in a case where a change fromthe former spectacle of the same side is adopted, adjustment of ±0.75 D(three steps) is made with respect to the S value or the C value (StepsA-5, B-7, C-14, etc.), an arrangement may be provided such that anadjustment amount of ±0.50 D (two steps) is varied depending on the ageof the subject. The reason for this is that there are differences in theadaptive capability with respect to the change in the powers of theformer spectacles depending on the age. A young person is capable ofadapting himself or herself even if there is a change of three steps(0.75 D) with respect to the powers of former spectacles, but as the agebecomes higher, a change of two steps (0.50 D) generally becomes a limitin adaptation. Accordingly, if an attempt is made to change theadjustment amount of the prescription powers depending on the adaptivecapability of the eye being examined, it is possible to provide aprescription which is more suitable for the wearer. In the case wherethe adjustment amount of the power is changed depending on the age, thefollowing procedure is taken. In the automatic adjustment program, forexample, two kinds of power adjustment amounts are prepared, includingthree steps (0.75 D) and two steps (0.50 D) depending on whether the ageis greater than or equal to a certain age (38 years of age) (or morekinds may be provided). When the optometric program is in progress, ifthe advance switch 36 is pressed after completion of testing forconfirming the stereoscopic vision, an operational instruction forentering "less than 38 years of age" or "38 years of age or more" as theage of the subject is displayed in a lower portion of the screen. If theexaminer presses a function switch corresponding to either one of theoperational instructions, the apparatus calculates rough powers by usingthe aforementioned preset adjustment amount in correspondence with aninput signal.

In addition, although the arrangement adopted in the embodiment is suchthat the automatic adjustment program is executed upon obtaining aninput signal by the advance switch 36, this automatic adjustment programcan be executed in the manual optometry as well if necessary data hasbeen inputted thereto. In the manual optometry, if the "prescription"switch in the group of input-data designating switches 38 is pressedwhile the shift switch 44 is pressed, the automatic adjustment programis executed. In this case as well, the power adjustment amount may bechanged depending on the age of the subject.

Furthermore, although, in the above-described embodiment, the correctionamounts ΔS1, ΔS2, ΔC1, and ΔC2 in the correction processing A1 to D1 areobtained by calculation, tables may be prepared in advance respectively,and the correction amounts ΔS1, ΔS2, ΔC1, and ΔC2 in the correctionprocessing A1 to D1 may be obtained on the basis of the tables.

<Adjustment of Correction Power for Far Use--(2) Adjustment by Examiner>

If rough powers of prescription values are prepared by the automaticadjustment program, the results are displayed on the display 30. FIG. 17is a diagram illustrating an example of the screen of the display 30after the automatic adjustment. The central display portion 80 ischanged to a prescription mode, the rough powers which have beenautomatically adjusted by the apparatus as the S values and the C valuesin the display, and a message to the effect that the powers for far usehave been corrected is displayed in the lower portion of the centraldisplay 80. Optical systems corresponding to the automatically adjustedpowers are set in the test windows of the subjective-typerefractive-power measuring device 2, and test targets (charts) providedin a set of targets (charts) with visual acuity values ranging from 0.9to 1.2 are presented from the target (chart) presenting device. Whileconfirming the appearance of the adjusted power, the examiner makes fineadjustment of the correction power for far use by means of the switchoperation.

The apparatus has a control program for manual adjustment whereby thepower of the item to be adjusted is changed if a switch input is made onthe basis of the hyperopia or myopia, the presence or absence ofastigmatism (cylinder), and the presence or absence of obliqueastigmatism (cylinder) which are provided by the rough powers of theprescription values calculated by the automatic adjustment program. Whenthe automatic adjustment program has been executed, if the changeoverswitch 43a or 43b is operated after obtaining a response from thesubject on the appearance, the power of the item to be adjusted changes.

Hereafter, a description will be given of the manual adjustment based onthe control program of the apparatus (see FIGS. 18 and 19).

[Manual Adjustment A: In the Case of Adjustment of Powers of HyperopiaWithout Astigmatism (Cylinder)]

The subject is allowed to visually confirm the presented targets(charts) through the optical systems set in the test windows of thesubjective-type refractive-power measuring device 2, and an appearanceat the automatically adjusted powers is confirmed. If the subject issatisfied with the appearance, the adjustment ends. If the target(chart) is difficult to view, the "STRENGTHEN" switch 43b is pressed. Asa result of this input signal, a determination is made as to whether ornot the S value of the adjusted power of each eye is greater than 0, andif it is determined that it is greater than 0, -0.25 D is added to the Svalue of each eye. This operation is repeated until the subject issatisfied with the appearance, or the S value of each eye becomes 0.After the S value of one eye has become 0, adjustment is made until theS value of the other eye becomes 0. In the correction of hyperopia,adjustment to the myopic side in which case the S value becomes minus isundesirable, so that when the S value has become 0, a warning is issuedby the buzzer 54, informing the examiner that the input is impossible.Incidentally, in this flow, the input by the "WEAKEN" switch 43a is notaccepted, and when this switch is pressed, a buzzer sound is issued in asimilar manner.

[Manual Adjustment B: In the Case of Adjustment of Powers of MyopiaWithout Astigmatism (Cylinder)]

The examiner confirms the appearance at the automatically adjustedpowers. If the target (chart) is difficult to view, the "STRENGTHEN"switch 43b is pressed. As a result of this input signal, a determinationis made as to whether or not the S value of the adjusted power isgreater (smaller in the absolute value) than the S value of binocularperfect correction, and if it is greater, -0.25 D is added to the Svalue of each eye. The input by the "STRENGTHEN" switch 43b is accepteduntil both the adjusted S values of both eyes reach the limits of thevalues of binocular perfect correction. When the limits are reached, abuzzer sound is issued (in the following description as well, a buzzersound is issued when a limit is reached).

When an uneasy sensation (the power is strong) is present in theconfirmation of the appearance, the "WEAKEN" switch 43a is pressed. Adetermination is made as to whether or not the S value of each eye islower than -0.25 D (whether it is 0), and if the S value is not lowerthan -0.25 D (it is not 0), +0.25 D is added to the S value of each eye.After the S value of one eye has become -0.25 D, adjustment is madeuntil the S value of the other eye becomes -0.25 D.

[Manual Adjustment C: In the Case of Adjustment of Powers of Hyperopiaand Astigmatism (Cylinder) Which is Not Oblique Astigmatism (Cylinder)]

The examiner confirms the appearance at the automatically adjustedpowers. If the target (chart) is difficult to view, the power adjustmentis made in the same way as with the manual adjustment A by pressing the"STRENGTHEN" switch 43b.

If the subject has expressed an uneasy sensation, the "WEAKEN" switch43a is pressed. A determination is made as to whether or not the C valueof each eye is lower than -0.25 D (whether it is 0), and if the C valueis not lower than -0.25 D (it is not 0), +0.25 D is added to the C valueof each eye. If the C value is lower than -0.25 D, a buzzer sound isissued.

[Manual Adjustment D: In the Case of Adjustment of Powers of Myopia andAstigmatism (Cylinder) Which is Not Oblique Astigmatism (Cylinder)]

The examiner confirms the appearance at the automatically adjustedpowers. If the target (chart) is difficult to view, the power adjustmentis made in the same way as with the manual adjustment B by pressing the"STRENGTHEN" switch 43b.

If the subject has expressed an uneasy sensation, the "WEAKEN" switch43a is pressed. A determination is made as to whether or not both the Svalue and the C value of each eye are lower than -0.25 D (whether theyare 0), and if both the S value and the C value of each eye are notlower than -0.25 D (they are not 0), the power of the C value or the Svalue is adjusted consecutively by the number of inputs by the switch43a through a combination of the S value and the C value as describedbelow. Through a first input signal, +0.25 D is added to the C value ofeach eye. Through a second input signal, the +0.25 D added to the Cvalue in the first input is returned, and +0.25 D is added to the Svalue. Through a third input signal, +0.25 D is added to the C valuewith respect to the power of the second adjustment. Thereafter, by thenumber of inputs by the switch 43a, the operation is repeated until boththe S value and the C value reach their limits (when either one of the Svalue and the C value reaches a limit first, the power of the othervalue is dropped).

[Manual Adjustment E: In the Case of Adjustment of Powers of ObliqueAstigmatism (Cylinder) and Hyperopia]

The examiner confirms the appearance at the automatically adjustedpowers. If the target (chart) is difficult to view, the power adjustmentis made in the same way as with the manual adjustment A by pressing the"STRENGTHEN" switch 43b.

If the subject has expressed an uneasy sensation, the "WEAKEN" switch43a is pressed. A determination is made as to whether or not the C valueof each eye is lower than -0.25 D (whether it is 0), and if the C valueis not lower than -0.25 D (it is not 0), the C value or the A value ofeach eye is adjusted by the number of inputs by the switch 43a on thebasis of a combination of the C Values and the A values.

A description will be given of the power adjustment in the combinationof the C values and the A values in oblique astigmatism (cylinder). Whenan uneasy sensation in spatial vision in oblique astigmatism (cylinder)is alleviated, adjustment is made for causing the axis to approach ahorizontal direction or vertical direction. At this time, if the axisdetermined in perfect correction is rotated, new astigmatism (cylinder)is produced. If it is assumed that the C value of perfect correction isC₁, and the A value is θ₁, and that the C value for prescription is C₂,and the A value is θ₂, the newly produced astigmatic (cylindrical) powerC₀ and its axial angle θ₀ can be expressed as follows:

    (a) tan 2θ.sub.0 =(C.sub.1 sin 2θ.sub.1 -C.sub.2 sin 2θ.sub.2)/(C.sub.1 cos 2θ.sub.1 -C.sub.2 cos 2θ.sub.2)

    (b) C.sub.0 =(C.sub.1 sin 2θ.sub.1 -C.sub.2 sin 2θ.sub.2)/sin 2θ.sub.0

When an uneasy sensation is present, the astigmatic (cylindrical) poweris decreased by inputs by the "WEAKEN" switch 43a, which results in anincrease in newly produced astigmatism (cylinder), i.e., residualastigmatism (cylinder). Since the step of change in the astigmatic(cylindrical) power in the embodiment is set at 0.25 D, the power isadjusted in such a manner that the power changes by portions ofapproximately 0.12 D in terms of the C-value equivalent by the number ofinputs by the switch 43a on the basis of the above-described formulae,so that the residual astigmatic (cylindrical) power due to the rotationof the axis is brought to an intermediate level (about 0.12 D) of thestep of change 0.25 D. In the first input by the switch 43a, the axialangle for each eye is first adjusted so that the power changes by anapproximately 0.12 D portion in terms of the C-value equivalent. In thesecond input, the axial angle is returned to cause a change by anotherapproximately 0.12 D portion, and the C value of each eye is dropped bythe 0.25 D portion. In the third input, the axial angle is adjusted tocause a change by the approximately 0.12 D portion with respect to thesecond input. Thus, astigmatism (cylinder) is adjusted on the basis ofthe relationship between the number of inputs by the switch 43a and thecombination of the C value and the A value (refer to a specific exampleshown in FIG. 20). After the C value of one eye has become -0.25 D,adjustment can be made until the C value of the other eye becomes -0.25D.

It should be noted that the adjustment of astigmatism (cylinder) can bemade not on the basis of the above-described calculation but on thebasis of a table prepared in advance.

[Manual Adjustment F: In the Case of Adjustment of Powers of ObliqueAstigmatism (Cylinder) and Myopia]

The examiner confirms the appearance at the automatically adjustedpowers. If the target (chart) is difficult to view, the power adjustmentis made in the same way as with the manual adjustment B by pressing the"STRENGTHEN" switch 43b.

If the subject has expressed an uneasy sensation, the "WEAKEN" switch43a is pressed. A determination is made as to whether or not both the Svalue and the C value of each eye are lower than -0.25 D (whether theyare 0), and if both the S value and the C value of each eye are notlower than -0.25 D (they are not 0), S, C, and A of each eye areadjusted by the number of inputs by the switch 43a through a combinationof S, C, and A. This adjustment is also made by processing which issimilar to that in the case of the above-described manual adjustment E.In the first input, the axial angle is first adjusted so that the poweris decreased by an approximately 0.12 D portion in terms of the C-valueequivalent. In the second input, the axial angle is returned, and the Cvalue is decreased by an approximately 0.25 D portion. In the thirdinput, the portion of change in the C value in the previous input isreturned, and the S value is decreased by a 0.25 D portion. In thefourth input, the S value in the previous input is kept as it is, andthe power is decreased by an approximately 0.12 D portion in terms ofthe C value equivalent by adjustment of the axial angle. Thereafter,this procedure is repeated in order. After the C value of one eye hasbecome -0.25 D, adjustment can be made until the C value of the othereye becomes -0.25 D. After the S value of one eye has become -0.25 D,adjustment can be made until the S value of the other eye becomes -0.25D.

Through the above-described manual adjustments A to F, the state of thesubject's vision is confirmed, a response for it is obtained, and inputsare made by either the switch 43a or the switch 43b, whereby the powersof appropriate items can be automatically adjusted. For this reason,even an inexperienced examiner is able to easily adjust the powers forfar use without being confused about the items to be adjusted, theirdirections, and switch operations.

It should be noted that, in the prescription mode in manual adjustment,each time the switch 43a or 43b is pressed, the immediately precedingprescription power data are consecutively stored in the memory of theapparatus, and, as shown in FIG. 21, a display 90 is given in a lowerportion of the operation explanation area 82 to the effect that adjustedpowers, which have been consecutively stored, such as prescriptionvalues 2, prescription values 3, . . . , are provided for prescriptionvalues 1 of the automatically adjusted powers calculated by theapparatus. If a relevant function switch 45 corresponding to eachprescription value in the display 90 is pressed, the optical systemdisposed in the test window of the subjective-type refractive-powermeasuring device 2 and the display in the central display portion 80 areinstantly changed over, and a comparison of the adjusted powers can bemade instantly. It goes without saying that the item to be adjusted andits powers can be manually changed by designating the mode by the switchS, C, or A of the group of mode-change designating switches 37, and byrotating the dial switch 42 clockwise or counterclockwise. If a relevantfunction switch 45 corresponding to a "COPY" display 91 which is adisplay of an operational instruction is pressed, that data can becopied, changed manually, and stored in the memory.

In addition, if the mode is set in the prescription mode, a plurality ofitems of reference data, which are the results in the previous testmodes, are displayed on the left- and right-hand sides of the centraldisplay portion 80. The example of the screen shown in FIG. 17 showsfirst left and right displays 81a for displaying spectacle values, whichare the results of the test mode before last, and their confirmed visualacuity values, as well as second left and right displays 81b fordisplaying subjective values of monocular perfect correction, which arethe results of the test mode before last, and their confirmed visualacuity values (when the former spectacle data is not available, unaidedvisual acuity values are displayed). As a result, the examiner is ableto readily confirm the data obtained in advance with respect to thepresent measurement mode. In particular, this arrangement is convenientsince, in the stage for adjusting the prescription powers, adjustmentcan be made while making a comparison by simultaneously viewing thespectacle values and the subjective values of monocular perfectcorrection or the like. Further, since the visual acuity values of theformer spectacles and visual acuity values in the subjective test ofmonocular perfect correction are displayed, it is possible to ascertainto what power the visual acuity of the subject can be ensured in theadjustment of the prescription powers and to what power an increase invisual acuity can be expected, so that this is useful in the adjustmentfor prescription.

It should be noted that although in the example of the screen shown inFIG. 17 two kinds of data on the first and second left and rightdisplays are used in the display of the reference data, three or morekinds of data may be displayed. How many kinds of data are to bedisplayed is designated in advance in the setting of parameters in themenu screen prior to the examination.

In addition, although an optometric program is used in the embodiment,it is, of course, possible to display a plurality of items of referencedata in the manual examination as well. At what stage the reference datais to be displayed may be set in advance, or the reference data may bedisplayed when a plurality of items of test data have been inputted.

When the display of the reference data is changed to other data, thefollowing procedure is taken. For example, when it is desirable to viewobjective value data in the example of the screen shown in FIG. 17, theobjective switch of the group of input-data designating switches 38 ispressed while the shift switch 44 is pressed. The subjective value dataof monocular perfect correction shifts to the first left and rightdisplays 81a, while the objective value data invoked from the memory isdisplayed in the second left and right displays 81b. Thus, it ispossible to freely invoke and display only the data which the examinerwishes to view, without changing the present measurement mode.

<Examination for Near Use>

After adjustment of the correction powers for far use has been made, theadvance switch 36 is pressed to proceed to an ensuing test. Since amessage is displayed on the screen of the display 30, inquiring whetheran examination for near use is required, when the examination for nearuse is to be effected, a relevant function switch 45 is pressed incompliance with the operational instruction. Subsequently, anoperational instruction for entering the age of the subject is displayedon the screen (when the age has already been entered at the time ofinquiry, this step may be omitted). If a relevant function switch 45corresponding to that operational instruction is pressed, the apparatusissues an operating signal to the subjective-type refractive-powermeasuring device 2. Optical systems of values of binocular perfectcorrection are set in the test windows of the subjective-typerefractive-power measuring device 2, and addition powers estimated to berequired on the basis of the inputted age (as the addition powers, thesetting of halves of the estimated values or a setting which is threestages (0.75 D) weaker or the like are also possible) as well as XClenses for near use are set therein. In addition, if a signal forconducting the examination for near use is entered, the flappingmechanism of the subjective-type refractive-power measuring device 2 isdriven, so that the lens units 10 are made to converge at an angle ofconvergence which corresponds to a near-use distance 35 cm. Thecontroller 5 is set in the addition mode, and the spherical powers canbe added by means of the dial switch 42 and the like. The examinerpresents a near-use target (chart) of a cross grid at a distance of 35cm in front of the subject's eyes. The addition powers for both eyes aremeasured, and the addition powers are entered.

After the addition powers have been entered, the advance switch 36 ispressed. The apparatus, upon receipt of the input signal, shifts thescreen to one for confirming whether or not the subject wears thespectacles for near use for the first time. If the subject wears themfor the first time, a relevant function switch 45 is pressed andadjustment is made for adding -0.25 D as the addition power. If thesubject does not wear the spectacles for near use for the first time, arelevant function switch 45 for leaving the addition powers as they areis pressed. The apparatus converts into differential addition powers thedifference in the S value and the difference in the equivalent sphericalC value, which were adjusted for far use, from the values of binocularperfect correction, and values in which these differential additionpowers are subtracted from the measured addition powers are calculatedas adjusted addition powers. However, if these values have become minus,the addition powers are set at 0. The adjusted values are displayed onthe screen of the display 30, and a message to the effect that theaddition powers have been adjusted is displayed thereon.

Subsequently, the examiner sets a visual test chart for near use forconfirming visual acuity, and confirms that the visual acuity value isnot lower than 0.7. If it is lower, visual acuity is confirmed. A checkis made as to whether the visual acuity improves by adding +0.25 D tothe ADD value of each eye. If the visual acuity improves, another +0.25D is added to the ADD value of each eye. If the visual acuity remainsunchanged or drops, -0.25 D is added to the ADD value of each eye toreturn to lower values. The addition powers are thus determined.

[Confirmation of the Appearance of Powers for Far Use in ConvergedState]

After determination of the addition powers, the following procedure istaken when allowing the subject to confirm to what extent it isdifficult to view a target (chart) for near use if it is viewed with theadjusted powers for far use. The examiner presses the ADD switch in thegroup of switches 37. If this switch signal is inputted, the apparatussets the subjective-type refractive-power measuring device 2 as it is inthe converged state, and disposes in the test windows optical systemswith powers for far use in which the addition powers have been canceledand which have been finally adjusted. The subject is allowed to view thetarget (chart) for near use in this state. Next, if the ADD switch ispressed again, the apparatus returns the canceled addition powers. Thesubject is allowed to view again the target (chart) for near use in thestate of the prescribed addition powers. Thus, since the state of thepowers for near use and the state of the powers for far use can beinstantly changed over with the subjective-type refractive-powermeasuring device 2 set in the converged state, the subject is allowed toactually feel the difference in the appearance clearly.

[Conversion of Powers to Different Near-Work Distance]

In addition, in the examination for near use, addition powers at apredetermined distance (in this embodiment, 35 cm) are obtained, butthere are cases where a necessary near-work distance is different fromthe distance in the examination for near use depending on subjects. Inthis case, it is necessary to adjust the addition powers at thenear-work distance desired by the subject. If the required near-workdistance is inputted, this apparatus is capable of changing the measuredpowers for near use to the powers for near use at the inputted distance.

A description will be given of a method of conversion of the powers fornear use to a different near-work distance which is effected by theapparatus.

If it is assumed that the addition power measured at a near-use testdistance f(m) is ADD(f), the accommodative power necessary for thenear-use test distance f can be considered to be 1/f, so that theaccommodative power which the eye being examined was able to use is1/f-ADD(f). In contrast, if accommodative power necessary for adifferent near-work distance f'(m) is assumed to be 1/f', the additionpower ADD(f') necessary for this distance can be set as

    ADD(f')={1/f'-(1/f-ADD(f))}

However, in the calculation of the power, the power is rounded off to acloser measuring step (in the embodiment, 0.25 D step).

The operation of conversion to a different near-work distance iseffected as follows. After completion of the examination for near use,if the advance switch 36 is pressed, an operational instruction 92indicating a necessary near-work distance is displayed on the displayscreen, as shown in FIG. 22. The examiner presses a relevant functionswitch 45 corresponding to the necessary distance. On the basis of theabove-described calculation, the apparatus calculates the addition powerby converting the addition power obtained in the measurement into anaddition power of the inputted distance. The converted addition powerswhich are calculated are displayed in ADD columns of the central displayportion 80. As a result, the examiner is able to readily ascertainaddition powers at the near-work distance desired by the subject.

Incidentally, a plurality of different near-work distances may beentered. Each time a relevant function switch 45 corresponding to thenecessary near-work distance is pressed, the converted powers aredisplayed. When the conversion of powers into those for a differentnear-work distance, or when unnecessary, the advance switch 36 ispressed.

In addition, the converted addition power portions may be imparted tothe optical systems disposed in the test windows of the subjective-typerefractive-power measuring device 2, so as to confirm the appearancewith addition power for a different near-work distance. Further, thesubjective-type refractive-power measuring device 2 may be arranged toconverge in correspondence with the near-work distance, so as to confirmthe appearance by presenting a visual test chart for near use at anecessary near-work distance.

If all the tests are completed and prescription values have beendetermined in the above-described manner, the print switch 40 is pressedto print out the results of measurement. FIG. 23 shows an example of theprint. Prescription values for far use in the S value, the C value, andthe A value are printed in a print portion 101 of a FINAL column whichshows prescription values. Addition powers at the near-use test distanceof 35 cm are printed in a print portion 102 therebelow. In a case wherea different near-work distance has been inputted, the converted additionpowers, together with the inputted distance, are printed in a printportion 103 of the print portion 102. In a case where a plurality ofnear-work distances have been inputted, the addition powers, togetherwith the inputted distance, are further printed therebelow.

In a FAR+ADDITION column 104, prescription values for near use in the Svalue, the C value, and the A value are printed after processing iseffected by the apparatus for adding an addition power portion to the Svalue of prescription for far use. Thus, during printout, since theprescription values for near use are printed separately from theprescription values for far use, in cases where monofocal lenses fornear use, for example, are prepared, the examiner is able to readily andaccurately ascertain their values.

In the above-described embodiment, the display of a warning promptingthe exercise of caution to the examiner with respect to the possibilityof intervention by accommodation may not be based not on the objectivevalue data, and a message prompting the exercise of caution such as "Hasaccommodation been sufficiently removed?" may be displayed at a stagewhere perfect correction values for one eye have been obtained and ifthe measured value in terms of the SE value is on the plus side (may bethe plus side or a minus of a weak power, in the same way as describedabove). Further, a message prompting the exercise of caution may bedisplayed in cases where the effect of accommodation is unnegligible,such as when, after making a comparison with the inputted objectivevalue data and former spectacle data, the plus power of a perfectcorrection value has dropped below the plus power of the inputted data(+1.50 D→+0.50 D, etc.), or when the minus data has changed to the plusside. This gives a clue to the examiner in determining whether closeexamination is required, before proceeding to an adjustment stage. Thesemessages may be displayed only when, in particular, the age of a youngperson (e.g., 15 years of age or younger) has been inputted.

In addition, a message to the effect that caution should be exercised tothe intervention by accommodation may be displayed not on the basis ofthe inputted power data or measured powers but at a start of examinationif the age less than or equal to a certain age (which may be set freelyin the setting of parameters) has been inputted. Alternatively, amessage prompting the exercise of caution may be displayed after perfectcorrection values have been obtained.

In addition, with this apparatus, it is possible to conduct visualfunction tests including near and far horizontal/vertical phoria testsand convergence and divergence tests. Methods of these tests will bedescribed with reference to the flowcharts shown in FIGS. 24 to 35.

In the apparatus of this embodiment, a plurality of optometric programsin which test items and test procedures are set in advance are stored inthe memory 51, so that the examiner is able to select a mode of theoptometric program conforming to the examination policy. As the modes ofthe optometric programs, a program A for a standard test and a program Bfor a simplified test have been prepared, and a program C, a program D,and a program E in which the examiner has written and inputted can beprepared. When conducting visual function tests including near and farhorizontal/vertical phoria tests and convergence and divergence tests,programs for the visual function tests are inputted in advance in theprogram C, the program D, or the program E (the program C may be usedfor the standard test, and the programs D and E for simplified tests).In addition, the procedures of programs for the visual function testsare set in advance, and if one test item is finished, the examiner isable to proceed to an ensuing test item by pressing the advance switch36. Incidentally, the procedure of this program is given as one example,and can be rearranged according to the examiner's preference.

With respect to a subject for whom it has been judged that a visualfunction test is required due to an eye complaint such as the difficultyin obtaining stereoscopic vision, or an eye complaint such as diplopiaor asthenopia (visual fatigue), after the optometric program shown inFIG. 5 is finished, the optometric program modes (A, B, C, D and E) areconsecutively changed over by pressing the program start key 35 whilepressing the shift switch 44, so as to select and start the visualfunction testing program inputted in the program C, program D or theprogram E. Incidentally, since such visual function tests can beeffected if perfect correction values are determined in the refractivepower test, the visual function tests may be implemented prior toeffecting the adjustment of correction powers for far use.

It should be noted that, in this examination, a pair of rotary prismsare disposed in the test windows 11 of the subjective-typerefractive-power measuring device 2. As for the rotary prisms disposedon the disks, the pair of prisms having the same powers are coupled toeach other by means of a gear and the like, and the pair of prisms arerotated in opposite directions by the same angles by turning the dialswitch 42, so as to change the powers.

<Far Horizontal Phoria Test--FIG. 24>

A prism separation method is adopted for the far horizontal phoria test.In the test windows of the subjective-type refractive-power measuringdevice 2, a 6 ΔB.U. (base up) fixed prism is placed on the right eyeside, and a rotary prism is placed on the left eye side in the B.I.(base in)/B.O. (base out) directions. The smallest letters which thesubject can read correctly or letters slightly larger than the same arepresented as the target (chart) in a vertical row. The examiner confirmsthe subject that the target (chart) is divided into two upper and lowersections. Then, after the left eye of the subject is covered, and thecover is removed, the examiner confirms the subject whether the target(chart) is deviated in the horizontal direction. If deviation is notpresent, the examiner presses the advance switch 36 to proceed to anensuing test item, and the determination that far horizontal phoria isnot present is automatically stored (The measured value is automaticallystored as 0.).

If the deviation is present, a check is made as to on which of the leftand right sides the lower section of the target (chart) was viewed. Ifit was viewed on the right side, then it is the case of esophoria, sothat the examiner rotates the dial switch 42 clockwise in accordancewith advice 110 shown in FIG. 36 to effect correction by adding the B.O.prism, and adjustment is made until the upper and lower sections of thetarget (chart) are aligned (until deviation disappears). If the lowersection of the target (chart) was viewed on the left side, then it isthe case of exophoria, so that the examiner rotates the dial switch 42counterclockwise to effect correction by adding the B.I. prism, andadjustment is made until the upper and lower sections of the target(chart) are aligned (until deviation disappears). After confirmation ismade from the subject that there is no longer the deviation in thetarget (chart), the advance switch 36 is pressed to proceed to anensuing test item. The measurement values upon completion of theadjustment are automatically stored.

<Far Vertical Phoria Test--FIG. 25>

The prism separation method is adopted for the far vertical phoria testas well. In the two test windows of the subjective-type refractive-powermeasuring device 2, a 10 ΔB.I. fixed prism is placed on the left eyeside, and a rotary prism is placed on the right eye side in theB.U./B.D. (base down) directions. The smallest letters which the subjectcan read correctly or letters slightly larger than the same arepresented as the target (chart) in a horizontal row. The examinerconfirms the subject that the target (target) is divided into two leftand right sections. Then, after the right eye of the subject is covered,and the cover is removed, the examiner confirms the subject whether thetarget (chart) is deviated in the vertical direction. If deviation isnot present, the examiner presses the advance switch 36 to proceed to anensuing test item, and the determination that far vertical phoria is notpresent is automatically stored (The measured value is automaticallystored as 0.).

If the deviation is present, a check is made as to which of the left andright sections of the target (chart) was viewed on the upper side(higher). If the left side is viewed on the upper side (higher), then itis the case of right eye hyperphoria, so that the examiner rotates thedial switch 42 clockwise in accordance with advice 111 shown in FIG. 37to effect correction by adding the B.D. prism, and adjustment is madeuntil the left and right sections of the target (chart) are aligned(until deviation disappears). If the right section of the target (chart)was viewed on the upper side (higher), then it is the case of left eyehyperphoria, so that the examiner rotates the dial switch 42counterclockwise to effect correction by adding the B.U. prism, andadjustment is made until the left and right sections of the target(chart) are aligned (until deviation disappears). After confirmation ismade from the subject that there is no longer the deviation in thetarget (chart), the advance switch 36 is pressed to proceed to anensuing test item. The measurement values upon completion of theadjustment are automatically stored.

<Far Divergence Test--FIG. 26>

In the test windows of the subjective-type refractive-power measuringdevice 2, the pair of rotary prisms are disposed on both eye sides inthe B.I./B.O. directions. The smallest letters which the subject canread correctly or letters slightly larger than the same are presented asthe target (chart) in a vertical row. By rotating the dial switch 42counterclockwise in accordance with advice 112 shown in FIG. 38 to addthe B.I. prism, the examiner confirms the subject whether the target(chart) blurred. If blur is not present, the dial switch 42 is rotatedfurther counterclockwise to add the B.I. prism. Incidentally, at thistime, even if the dial switch 42 is rotated clockwise, the B.O. prism isnot added. If blur is present, a "BLUR" button 113 in the group offunction switches 45 is pressed, and the value of the amount of prism atthe blurred point is stored.

Then, the dial switch 42 is rotated further counterclockwise to add theB.I. prism, and the subject is confirmed whether the target (chart) wasviewed as if there were two targets (charts). If it was not viewed as ifthere were two targets (charts), the B.I. prism is further added in thesame way as described above. If the target (chart) was viewed as ifthere were two targets (charts), a "BREAK" button 114 in the group offunction switches 45 is pressed, and the value of the amount of prism atthe broken (separated) point is stored.

This time, the dial switch 42 is rotated clockwise to decrease the B.I.prism, and the subject is confirmed whether the target (chart) wasviewed as one (returned). If it was not viewed as one, the dial switch42 is rotated further clockwise to decrease the B.I. prism. If thetarget (chart) was viewed as one, a "RECOVERY" button 115 in the groupof function switches 45 is pressed, and the value of the amount of prismat the recovered point is stored.

<Far Convergence Test--FIG. 27>

In the test windows of the subjective-type refractive-power measuringdevice 2, the pair of rotary prisms are disposed on both eye sides inthe B.I./B.O. directions. The smallest letters which the subject canread correctly or letters slightly larger than the same are presented asthe target (chart) in a vertical row. By rotating the dial switch 42clockwise in accordance with advice 116 shown in FIG. 39 to add the B.O.prism, the examiner confirms the subject whether the target (chart)blurred. If blur is not present, the dial switch 42 is rotated furtherclockwise to add the B.O. prism. Incidentally, at this time, even if thedial switch 42 is rotated counterclockwise, the B.I. prism is not added.If blur is present, a "BLUR" button 117 in the group of functionswitches 45 is pressed, and the value of the amount of prism at theblurred point is stored.

Then, the dial switch 42 is rotated further clockwise to add the B.O.prism, and the subject is confirmed whether the target (chart) wasviewed as if there were two targets (charts). If it was not viewed as ifthere were two targets (charts), the B.O. prism is further added in thesame way as described above. If the target (chart) was viewed as ifthere were two targets, a "BREAK" button 118 in the group of functionswitches 45 is pressed, and the value of the amount of prism at thebroken (separated) point is stored.

This time, the dial switch 42 is rotated counterclockwise to decreasethe B.O. prism, and the subject is confirmed whether the target (chart)was viewed as one (returned). If it was not viewed as one, the dialswitch 42 is rotated further counterclockwise to decrease the B.O.prism. If the target (chart) was viewed as one, a "RECOVERY" button 119in the group of function switches 45 is pressed, and the value of theamount of prism at the recovered point is stored.

<Near Horizontal Phoria Test--FIG. 28>

The prism separation method is adopted for the near horizontal phoriatest. The same prisms as those of the far horizontal phoria test aredisposed in the test windows of the subjective-type refractive-powermeasuring device 2. As for the target (chart), one for near use, inwhich the smallest letters which the subject can read correctly orletters slightly larger than the same are presented in a vertical row,is set 40 cm in front of the eyes of the subject by the examiner. Thescreen of the display 30 is set in the near use mode, and the display of"FAR USE" at the upper right end of the central display portion 80changes to "NEAR USE," and the flapping mechanism of the subjective-typerefractive-power measuring device 2 is driven, thereby causing the lensunits 10 to converge at an angle of convergence corresponding to thenear-use distance of 40 cm. The examiner conducts the near horizontalphoria test in the same way as at the time of the far horizontal phoriatest.

<Near Vertical Phoria Test--FIG. 29>

The prism separation method is adopted for the near vertical phoria testas well. The same prisms as those of the far vertical phoria test aredisposed in the test windows of the subjective-type refractive-powermeasuring device 2. As for the target (chart), one for near use, inwhich the smallest letters which the subject can read correctly orletters slightly larger than the same are presented in a horizontal row,is set 40 cm in front of the eyes of the subject by the examiner. Theexaminer conducts the near vertical phoria test in the same way as atthe time of the far vertical phoria test.

<Near Divergence Test--FIG. 30>

The same prisms as those of the far divergence test are disposed in thetest windows of the subjective-type refractive-power measuring device 2.As for the target (chart), one for near use, in which the smallestletters which the subject can read correctly or letters slightly largerthan the same are presented in a vertical row, is set 40 cm in front ofthe eyes of the subject by the examiner. The examiner conducts the neardivergence test in the same way as at the time of the far divergencetest.

<Near Convergence Test--FIG. 31>

The same prisms as those of the far convergence test are disposed in thetest windows of the subjective-type refractive-power measuring device 2.As for the target (chart), one for near use, in which the smallestletters which the subject can read correctly or letters slightly largerthan the same are presented in a vertical row, is set 40 cm in front ofthe eyes of the subject by the examiner. The examiner conducts the nearconvergence test in the same way as at the time of the far convergencetest.

<Near Point of Convergence (NPC) Test--FIG. 32>

The examiner removes the lens units 10 of the subjective-typerefractive-power measuring device 2 from before the eyes of the subject,and causes the subject to view with both eyes a small target such as apenlight in the vicinity of 50 cm in front of both eyes of the subject.The examiner carefully observes both eyes of the subject while causingthe target to approach the root of the subject's nose. By using ameasure or the like, the examiner measures the position at which thesubject said the target began to be seen as if there were two targets(charts), or the position where the line of one eye or the lines of botheyes of the subject failed to move inward or divergence occurred, fromthe root of the nose, and that distance is inputted to a screen 120 inFIG. 40 by means of the dial switch 42. On the basis of the measured andinputted value of the distance, the apparatus automatically calculatesangles of convergence due to a meter angle and prism dioptry inaccordance with the following formulae, and stores the respectivevalues.

[Angle of Convergence Due to Meter Angle]

If it is assumed that the measured distance to the root of the nose is dcm, since the distance from the root of the nose to the center ofrotation of the eye is approximately 2.5 cm,

    1/(d×0.01+2.5×0.01)=M.A. (angle of convergence due to meter angle)

[Angle of Convergence Due to Prism Dioptry]

If the value of the angle of convergence due to a meter angle determinedabove is multiplied by the pupillary distance at far vision pd cm,

    M.A.×pd=Δ (angle of convergence due to prism dioptry)

<Near Point of Accommodation (NPA) Test--FIG. 33>

A pushup method is adopted for the near point of accommodation test. Theexaminer removes the lens units 10 of the subjective-typerefractive-power measuring device 2 from before the eyes of the subject(the lens units 10 may be used), and presents a near-use target (chart)with the smallest letters which the subject can read correctly at aposition of 40 cm before the eyes of the subject. While causing thetarget (chart) to approach the eye being examined, the examiner confirmsthe subject whether the target (chart) blurred. After confirming theposition where the blurring of the target (chart) occurred, the examinermeasures the distance from the position of occurrence of the blur to theroot of the nose of the subject, and inputs the measured value to ascreen 121 in FIG. 41 by means of the dial switch 42. On the basis ofthe measured and inputted value of the distance, the apparatusautomatically calculates the accommodative power in accordance with thefollowing formulae, and stores that value. Incidentally, the test may beeffected for one eye at a time or both eyes.

[Accommodative Power]

If the measured distance to the root of the nose=s cm, the accommodativepower=A, the accommodative power at near point=P, and the accommodativepower at far point=R, then P=1/(s×0.01), and A=P-R (R is 0 in perfectcorrection).

<Near Negative Relative Accommodation (NRA) Test--FIG. 34>

The examiner disposed the lens units 10 of the subjective-typerefractive-power measuring device 2 in front of the eyes of the subject,and presents a near-use target (chart) with the smallest letters whichthe subject can read correctly at a position of 40 cm before the eyes ofthe subject. The examiner rotates the dial switch 42 counterclockwise inaccordance with advice 122 in FIG. 42 to add the plus spherical lens,and confirms the subject whether the target (chart) blurred. If the bluris not present, the examiner rotates the dial switch 42 furthercounterclockwise to add the plus spherical lens. Incidentally, at thistime, even if the dial switch 42 is rotated clockwise, the minusspherical lens is not added. If the blur is present, the examinerpresses a "BLUR" button 123 in the group of function switches 45, andthe power of the plus spherical lens at the blurred point is stored.

This time, the examiner rotates the dial switch 42 clockwise to decreasethe plus spherical lens, and confirms the subject whether the target(chart) was seen clearly (returned). If the target (chart) was not seenclearly, the dial switch 42 is rotated further clockwise to decrease theplus spherical lens. If the target (chart) was seen clearly, a"RECOVERY" button 124 in the group of function switches 45 is pressed,and the power of the plus spherical lens at the recovered point isstored.

<Near Positive Relative Accommodation (PRA) Test--FIG. 35>

The examiner disposed the lens units 10 of the subjective-typerefractive-power measuring device 2 in front of the eyes of the subject,and presents a near-use target (chart) with the smallest letters whichthe subject can read correctly at a position of 40 cm before the eyes ofthe subject. The examiner rotates the dial switch 42 clockwise inaccordance with advice 125 in FIG. 43 to add the minus spherical lens,and confirms the subject whether the target (chart) blurred. If the bluris not present, the examiner rotates the dial switch 42 furtherclockwise to add the minus spherical lens. Incidentally, at this time,even if the dial switch 42 is rotated counterclockwise, the plusspherical lens is not added. If the blur is present, the examinerpresses a "BLUR" button 126 in the group of function switches 45, andthe power of the minus spherical lens at the blurred point is stored.

This time, the examiner rotates the dial switch 42 counterclockwise todecrease the minus spherical lens, and confirms the subject whether thetarget (chart) was seen clearly (returned). If the target (chart) wasnot seen clearly, the dial switch 42 is rotated further counterclockwiseto decrease the minus spherical lens. If the target (chart) was seenclearly, a "RECOVERY" button 127 in the group of function switches 45 ispressed, and the power of the minus spherical lens at the recoveredpoint is stored.

After the foregoing visual function tests are finished, if the menuswitch 32a is pressed to select the list of data, the table on S, C, A,ADD (addition power), and VA (visual acuity value) for far use shown inFIG. 44 is displayed. The examiner is able to see the following data bypressing the function key 45.

When invoking [data on S, C, A, ADD, and VA for far use--FIG. 44], a"FAR USE" button 128 and an "SCA" button 130 in the group of functionswitches 45 are pressed.

When invoking [data on S, C, A, ADD, and VA for near use--FIG. 45], a"NEAR USE" button 129 and the "SCA" button 130 in the group of functionswitches 45 are pressed.

When invoking [data on prism for far use (horizontal phoria, verticalphoria, convergence, and divergence)--FIG. 46], the "FAR USE" button 128and a "PRISM" button 131 in the group of function switches 45 arepressed.

When invoking [data on prism for near use (horizontal phoria, verticalphoria, convergence, and divergence)--FIG. 47], the "NEAR USE" button129 and the "PRISM" button 131 in the group of function switches 45 arepressed.

When invoking [data on NPC, NPA, NRA, and PRA for near use--FIG. 48],the "NEAR USE" button 129 and a "NPC" button 132 in the group offunction switches 45 are pressed.

When invoking [display of graph data and AC/A ratio (ratio betweenaccommodative convergence and accommodation)--FIG. 49], a "graph" button133 in the group of function switches 45 is pressed.

Further, by pressing "ANALYSIS 1-4" in the group of function switches 45shown in FIG. 49, the results of analysis and a method of prescriptionbased on the measurement values obtained from the foregoing visualfunction tests can be displayed on the screen. If an "ANALYSIS 1" button135 is pressed, the results of analysis and a method of prescriptionbased on the AC/A ratio and the eye position are displayed (see FIG.50). If an "ANALYSIS 2" button 136 is pressed, the results of analysisand a method of prescription based on the Sheard's criteria aredisplayed (see FIG. 51). If an "ANALYSIS 3" button 137 is pressed, theresults of analysis and a method of prescription based on the Percival'scriteria are displayed (see FIG. 52). If an "ANALYSIS 4" button 138 ispressed, the results of analysis and a method of prescription based onthe Morgan's system are displayed (see FIG. 53). The examiner is able tocorrect an error in the visual function of the subject in line with theresults of analysis and the method of prescription.

In accordance with the present invention, even a person who isinexperienced and unfamiliar with optometry is able to easily obtainappropriate prescription values, and is able to conduct analysis of thevisual function.

What is claimed is:
 1. An optometric apparatus for correcting refractionof an eye to be examined, comprising:a rotary prism for imparting aprism power to the eye to be examined; program storing means for storinga program for conducting examination by using said rotary prism; programadvancing means for advancing said program; prism-power storing meansfor storing a prism power of an expected state; and display means fordisplaying a result of examination.
 2. An optometric apparatus accordingto claim 1, wherein said program stored in said program storing meansincludes a program in which an operating method in an examinationprocess is displayed by said display means.
 3. An optometric apparatusaccording to claim 1, wherein said program stored in said programstoring means includes at least one of a horizontal phoria test, avertical phoria test, a divergence test, and a convergence test.
 4. Anoptometric apparatus according to claim 3, wherein tests for far use andnear use are included in each of said tests.
 5. An optometric apparatusaccording to claim 1, wherein said program stored in said programstoring means includes at least one of a near-point-of-convergence test,a near-point-of-accommodation test, and a near accommodation test.
 6. Anoptometric apparatus according to claim 5, further comprising:inputmeans for inputting a distance from a root of a nose at the time of saidnear-point-of-convergence test or said near-point-of-accommodation test;and calculating means for effecting a predetermined calculation on thebasis of the inputted distance.
 7. An optometric apparatus according toclaim 1, wherein the result of examination displayed by said displaymeans includes a result of analysis in which the result of examinationis analyzed.
 8. A controller for operating a subjective-typerefractive-power measuring device and a target presenting device in anoptometric apparatus, said controller comprising:a memory which storestherein a program for a visual function test to be executed afterperfect correction values for both eyes are obtained; a microcomputercircuit connected to said memory to control said subjective-typerefractive-power measuring device and said target presenting device inaccordance with said program; a switch section through which an examinercan control said subjective-type target presenting device and caninstruct whether a current test item of the visual function test shouldbe continued depending on a reply from a subject; and a display on whichan advice regarding how to control the subjective-type target presentingdevice is displayed if the examiner instructs, through said switchsection, that said current test item should be continued.
 9. Acontroller according to claim 8, wherein said memory automaticallystores therein a result of the current test item if the examinerinstructs that said current test item should not be continued.
 10. Acontroller designed for an optometric apparatus, comprising:a memorywhich stores therein a program for a visual function test including atleast one of horizontal phoria test, a vertical phoria test, adivergence test, a convergence test, a near-point-of-convergence test, anear-point-of-accommodation test, and a near accommodation test; amicrocomputer circuit connected to said memory; a switch sectionconnected to said microcomputer circuit; and a display connected to saidmicrocomputer circuit.